I think most, if not all people here have been in a "ended up becoming friends with HB cause she had a boyfriend she wouldn't dump" type of situation, and for me, it was just a non-stop ****tease. I got some though, with a price to pay though. Don't let yourself ever end up in this position, you'll regret it. Well, you might not regret it, but I definitely have, and always will.
(Expletives you find below were misspelt on purpose..didn't want to censor them cause I don't have anything to hold back here..)
The one and only time I let myself fall into this trap was back when I was a complete AFC with no experience at all. Today I still see myself as an AFC, but an AFC with progress. I still haven't become the type of person who can just meet and fuuck someone in a short time span without getting to know them for at least a week, but I've gotten a lot better at that over the years.
The HB I was hitting on ended up having a b/f, the same one for an entire year, and I dunno why it didn't stop me. I hung onto her for 6 months, playing the rebound position, hoping and waiting for her to finally drop him since I thought a year was too long for someone in high school to be invol..aaah you bastards all know how it goes down. Pure AFC action we're talking about here. I just look at it as needing to learn the mistakes first before making progress.
She kept breaking up with him about once every month, though the "break ups" would last for no more than a week. She didn't know how to get over a person. Luckily, this was a benefit for me, because I took us and our "friendship" from pecks on the cheek and light kino, to deep kissing and groping each other in the middle of hugging. She would start showing me her tits when they were hurting...I mean yea, she considered me to the one and only "best" guy friend.
Phone calls and outings where we were alone would end with "I love yous" and kisses on the lips, yet anytime strangers or friends were present, the lip kissing would go back into friendly cheek pecks, and the I love yous would return to standard goodbyes. On top of all of this, she was still telling me about how many times she screwed the b/f each week I didn't care though cause I was stupid, horny, and desperate back then.
For someone who was as hot as her, I'd easily take sloppy seconds.
Finally, after 4 and a half months of being her favorite friend, she cheated on him with me while in the middle of a longer than usual break up. Well... she saw it as cheating, but I saw it as her finally letting go of him. She got drunk with me (though I barely even reached a buzz) at her place one night while she was "separated" from him, we got into some discussion about people being sexually violated, and the next thing I know, we start poking and rubbing each other in the dirty areas, making a series of taunts at each other that sounded like "Oh yeah? Here's how that feels..." comments. I forgot what happened, but I started chasing her around her apartment, and then tripped and fell right on top of her. Panting and cracking up, right there I just make a quick smooch on her drunk (but hot) ass, but when I pull back after the kiss, she grabs my face and sticks her tounge into my mouth, and the rest is history fellas.
I felt like complete shiiit. Yeah, I finally got to bang the HB I wasted endless nights pursuing and enduring. It was definitely one of the most uncomfortable things I've ever done (worse than being stopped at a redlight next to a guy you just flipped off and honked at even though you know he could pound your ass with his eyes closed). I mean, to be f*cking someone so late after knowing them for too long, too many stories about her sex life, too much about what she hated and liked, without ever getting to contribute to it..Jesus..it's simply one of the worst things.
With her, I often felt like "I deserved to have humped this bittch by now," and when I finally got to, it just wasn't worth it. The last thing I gave a damn about about was whatever the hell her b/f would think, and I guess that makes sense, considering I wanted to steal her from the get go.
The next few days, we didn't call each other. When I finally decided to have a talk about what happened, she shot the conversation down by informing me that she got back with that coocksucking B/F of hers during the few days we hadn't spoken. At that point I was just furious and jealous as hell of the loser ass b/f. Since the day that I met him, I knew he didn't have a damn thing over me, but she was back with him yet again, even after she finally got a chance to let go.
No HB (well not necessarily all of them, but most) is going to want to become a full fledged girlfriend to a person she always had in mind as a friend. You better keep that in mind.
I was only friends with her a month or two longer, and for that period of time she took us all the way back to step 1...pecks on the cheek, no more I love yous, and shiiiitty ass kino. I got bored of being around her so much, didn't joke around anymore...the whole friendship turned into one humongous mindfuuck. Finally I couldn't take it any longer and told the HB I thought it was better if we didn't talk for a while, and that's how it ended. I don't even know if she ever told him. I did hear that she stayed with him for almost another year though.
I look back all the time and realize that I lost a really fun friend just cause I had a craving to stick my diick into her from the start. Do not become friends with an HB target you intend to fuuck one day, especially when she has a b/f, unless you have some clever fullproof scheme that makes you think you can steal her. I don't think any girl is worth that kind of hassle, no matter what she looks like or how great you think it would be to nail her juicy little cunnt. Once she even gets the notion of degrading you from possible hook up to plutonic friend, it's time to fold your cards. I try to avoid that type of circumstance as much as possible. If they have a boyfriend, I basically give up right there. Then again, that's why I'm still an AFC..
Going through the crap I went through, simply wasn't worth it in the end.
I know none of this directly answered the questions you had on your post, but at least it'll give you a perspective on how bad things can go if you let stupid shiit happen. I guess the whole point I was trying to make out of all of this was to tell you that unless you have more than a hunch that she'll drop a boyfriend for you, don't even bother putting her on high priority, no matter how hot she is. If she comes around to you, then take it. If not, don't bother. I'm never going to let myself enter a situation like that again though. You'll either steal the HB from the b/f early on, or you'll sit there with HER hearing about what it's like to have sex with HIM.