Since this thread has no posts answering your question, I'll try my best to help you out.
So from my understanding, there is a woman who you really adore and who you have developed great rapport with. However, the only problem is that she has a boyfriend and they have been together for 2.5 years. For starters, 2.5 years is quite a long time to be with somebody at the age of 18. (I'll assume she is either your age or younger.)
I personally would try to avoid getting yourself in this situation, and I would either find another girl or wait till they break up. I have had a DJ try and break apart me and my girlfriend, and unfortunately, it worked for him. You may not know the whole side of the story, and he may really like her just as much as you do. Just something to think about.
Anyway, she seems like she's already yours since she is already cuddling with you, etc. Nice job! The next time she brings up her boyfriend however, I would try to change the topic. She may only see you as a friend, since it seems she has already started to tell you all her problems with her boyfriend. Whenever a girl that you are talking to brings up the subject of her ex-boyfriend, you've got to immediately change the subject every time she does because the last thing you want is for her to think you are a "shoulder to cry on". You want to be the guy she talks about to other guys, not the guy she goes to explain her problems too, that's what a physicatrist is for!
Since they have been together for a long time, it's a very sticky situation. She may only want you for the fun and messing around (which explains how easy she was to get to cuddle with.) However, after a relationship that lasted that long its too soon to pressure her into a relationship, it could possibly scare her off. In a forum I recently visited, they explained to the DJ's that the best thing to do is to get her in a playful mood or at least happy (and most importantly not thinking about her ex and realizing how much fun she is having without him) then explain to her that you want her to be your girl but you don't want to rush anything. tell her that you'll move at her pace and if she wants you to back off a little and slow down all she has to do is say so and you will. Let her know you don't like to play games and if she wants to go out with you, she needs to tell you!
In addition, what you need is to use some boyfriend-destroyer liners, there are TONS on this forum! I have a post from a personal collection of mine that I kept because I found it to be very helpful to myself, and it may help you as well once you find some examples of lines you can use to "destroy" her boyfriend. Just look up "boyfriend-destroyers" in the search feature of this forum, and I guarantee there will be numerous results. If not, send me a PM and I will be glad to spend a couple of minutes to send you some great examples.
Anyway, here is the post that I mentioned about. (NOTE: I take completely no credit for the information below. I believe it was from the PUA forum. If I knew who the creator of the post was, I would credit him.)
If it's early in the sarge and she says, "I have a BF," this does NOT mean that it's time to do BF destroyers. This means that you did NOT attract her and that she could even be LYING to you because she doesn't want to talk to you. So... if you get this too soon, then you need to deal with more fundamental game issues first.
If she waits until later in the sarge and brings it up reluctantly, like, "Oh, I'm kinda seeing someone," then you know you're IN.
THE ULTIMATE BF DESTROYER:
Ignore it. Don't make an issue of it. The first time she brings up her BF, don't say anything more than, "That's cute." Just keep gaming her. You can break this rule later when you learn to calibrate.
If she brings it up again, there are a few techniques I have that work REALLY well to make take her BF out of her mind and put YOU in his place. (Well, at least make her forget about him for long enough to go home with you.)
They're all based on a few basic principles. Basically, you want to create a VOID in her life by letting her see that her BF is not fulfilling her needs. Then you show her that you are precisely her-void-shaped and ****ing you would make everything alright.
Remember these principles:
First, if you BASH her boyfriend, she will get DEFENSIVE and support him. You've just anchored good feelings towards her BF and BAD feelings towards you. Bad idea. This even happens if SHE starts bashing her BF and you AGREE with her. Second, if you try to convince her that you are better than her BF, the same thing will happen.Third, if you talk about how awesome her BF is and exaggerate it to impossible proportions and talk about how they are destined to be together forever, this will cause her to re-evaluate her BF in YOUR TERMS... and be disappointed. Fourth, if you talk about how horrible a BF YOU would be, and why she would never want to date you, she will start to relate that to HER experience with HER boyfriend. It's sometimes also effective if you do this ironically, telling her how WONDERFUL you would be and then describing all your horrible traits as if they were ideal.
Fifth, use future adventures projection to have her imagining the two of you together. Use this HEAVILY. I cannot stress this enough. Sixth, fractionate between a joking, tongue-in-cheek, "I'm just kidding" tone and serious, "Is he kidding?" tone depending on how into you she is and how attached she still is to her BF. Seventh, use false disqualifiers a LOT. Make excuses for why you can't be with her, especially ones that disqualify yourself. It helps if they are blatantly weak excuses. My favorite is that my other girls take up too much of my time as it is. Use these right after Future Adventures Projection too. Eighth, just pretend that the words "I have a boyfriend" have NO MEANING at all to you. Continue as if she never said it. Ninth, she is destined to be yours and you both know it. There is no element of NEEDINESS here.
Combine these principles (and others that I've forgotten, and anything IN10SE would care to add) and you can create your own BF Destroying material on the fly. Here are some routines that I've created while talking to girls:
(This is from a sarge with a SHB who is "kinda seeing" the manager of a trendy downtown club)
Me: "You're a lesbian, aren't you!"
Her: "I'm not a lesbian! But... er... I am kinda seeing someone. He's about this tall, dark hair [starts describing the manager, who I had seen her eating dinner with after the clubs closed the previous night]"
Me: "Well, it's a good thing that I like him."
Her: "Why?"
Me: "Well, because otherwise I'd just steal you from him, take you to a desert island, and spend a week drinking rum, sun-bathing, and skinny-dipping with you. [I could have gone on with the future adventures projection, but I decided not to.] But that will never happen. So, tell me, how long have you been 'kinda seeing' him?"
Her: "Oh, just a few weeks now."
Me: "Wow, you know, just from the way your eyes are all bright and your skin is glowing, I can tell that you are totally in love with this guy. In fact, I predict that a year from now, you will be happily married with 1.5 kids and a white picket fence." [said very tongue in cheek]
Her: "I don't want to get married, and I certainly don't want kids right now! I'm an independent woman!"
Me: "Of course you are. But he's just so perfect for you! I bet he buys you flowers every day you see him. I'm sure that he is always a perfect gentleman and never even LOOKS at another girl while the two of you are together." [note: I had been blatantly gaming girls all night, right in front of her, and getting #s.]
Other stuff to do and a general structure:
She mentions her BF and starts qualifying him somehow ("Oh, he's so X. I love him so much"). You use this when you start a FUTURE ADVENTURES PROJECTION:
"So I suppose that since I like him and I don't want to hurt his feelings and everything, we will have to conduct our moonlit tryst secretly. He must never know of our clandestine meetings."
Then you build up her BF with:
"You know what? It sounds like you guys are totally in love. I can totally tell that he's the PERFECT guy for you and you will ALWAYS be together. In fact, I bet he'll propose to you soon and you'll get married and have kids and live in a nice house with a white picket fence. And you know, I just couldn't live with myself if I ruined the rest of your life with him because he is your PERFECT BOYFRIEND."
Then she starts bashing her own boyfriend ("Well, sometimes he's mean to me. Blah blah blah") and you say, "Well, if I was your boyfriend, I wouldn't be like that at all. I would call you three times a day JUST to find out where you were and what you were doing and who you were with. I would get mad if you didn't call me EVERY day because I would love you SOOOOO much. I would go out drinking with the guys every weekend so you could have your personal space to do whatever it is that girls do... I don't know, cooking and cleaning and such. Oh, and I would forget all our anniversaries and break up with you on valentines day."
Summary:
So, the idea is:
She mentions the BF,
You ignore it.
She mentions him again,
You start three threads going:
One is future adventures projections of you and her having sex. But you use imagery that she can fantasize about (If you don't know, go read a romance novel) and disqualify yourself. ("Yeah, but that will never happen.") This raises buying temp. The second is a thread that describes him as the ideal boyfriend so his faults are amplified. This is a DHV. The third is a thread that describes you as a horrible boyfriend. You can do it ironically if you want. Basically, it's a DLV and a false-disqualifier.