First off: don't you hate it when you ask a question and nobody answers it?
Second: most of these guys are right. In 98% of these cases there aren't a series of steps to take. The interest will either be there or it won't. With that said, though, the fact that she's having regular sex with you is a decent enough sign to, at the very least, see if something is there.
Personally, I have had a few FWB situations where I really WAS in it just for the sex, but the girl, over time, ended up wanting more. The thing to do in order to make this happen is, ironically enough, nothing.
Yes, re-read that: DO NOTHING.
See, guys oftentimes have the terrible habit of doing the right things to get the girl to sleep with them, then trying to do the complete opposite when trying to get them in a relationship. My guess is you're trying to think of things you can say, or actions you can take, to turn her on further. This is the LAST thing you need to be doing.
I'll assume for the time being that this girl is not, as one of the other people commenting above said, a slvt. Hey, girls gotta get theirs sometimes too, right? BUT, here's where it gets interesting: if the girl likes you, she will start to feel odd that you're sleeping together regularly but NOT in a relationship.
She will start to play her own mind game with herself, convincing her ego that if you're the ONLY one she's currently sleeping with, she must like you. And, in order for her to convince herself that she's not being a slvt, she will have to eventually tell herself to figure out what your guys' "situation" is.
TRUST me, I've had this happen at least 3 times, and the situation is always the same: we hook up, we agree to be FWBs, I keep acting aloof, she starts getting more and more attached, and then one day... "so, what exactly ARE we?" pops up.
Until this happens - and it can take anywhere from 2 to 6 months, so if you're really trying to do this you need to have some patience - here's how you should act:
1. Don't be clingy
2. Don't be announcing your feelings all over the place
3. If you're texting her constantly, STOP IT, and only use the phone to make dates or hook-up meetings
4. Stop acting jealous or verbalizing jealousy - you want her to ponder WHY you're not so jealous, which will make her think you possibly have other options (and NEVER verbalize to her if you have other options or not)
5. Make sure when you two have sex you're making her orgasm or come close to it. If you can't, there are plenty of places online where you can read up on how to do it
6. Lastly, and most importantly, DO NOT ASK HER FOR A RELATIONSHIP. Again, if a woman likes you, she can only wait so long before wanting to ask you herself. And when she brings it up, make sure you negotiate the terms you want BEFORE saying you want to be her exclusively (i.e. "are you still talking to exes?" "Will you treat me on every 3rd date?" "How often a week will we have sex?" This last part may sound silly, but TRUST - anything that's going to annoy you in the relationship if it's not happening needs to be addressed BEFORE you're in it.)
Hope this helps!
