The girl still lives with her ex, what happened here?!

Background: I noticed this HB checking me out around university and had casual convos w/ her. Was pretty obvious she couldn’t keep her eyes off me. Found out she was living with her LTR (about 2 years). Exam after party, her “bf” is with her for 1st half of the night. she comes upto me and asks if I remember when I first met her.

She said, a few years ago at a party she came upto me and told me she loved me. I remember her now- She actually came up and said “I think your absolutely beautiful but I’m engaged”,then ran aways. She looks a lot different- far more attractive now. I figure the game» is on, so hold her hand and spend some time with her. She is receptive. then we have holidays for 2 months, so didn’t really figure on starting anything. I assume that her relationship must be on the rocks.

The situation: When we get back, on the first social reunion event, I make out with her. I am escalating quite a bit: hands up skirt, etc. We get back to hers, with her live-in ex bf and she does not let me escalate any further but there was some heavy petting. He comes out to see who she’s brought back. This feels awkward! I have seen this dude previously and he strikes me as a needy, possessive AFC.

Anyway I saw her once a week for about a month and a half and although we made out at the end of each “date”, she would not let me escalate further. We would send each other a few “update” texts throughout the weeks.

The last time I saw her we went out for dinner. Don’t worry- she paid half! I didn’t ask but she was telling me about how some peeps think it’s weird that she’s still living with her ex and seeing someone else but she would rather live with her ex then a lot of other peeps. In a few of our dates, she mentioned that her ex still hadn’t told his parents that they had broken up, even though it had been 6 months. Then we got a taxi back. I initially said my place but she changed it to her place, which I agreed with. but perhaps shouldn't have.

When we get back, her ex-bf is in her room, typing away on her computer. She asks him what he’s doing and he says he is reading emails of some drama in his law office that is occurring. She offers to get me a drink and asks her ex if he wants a tea (wtf?)
He doesn’t. So we’re sitting on the sofa and I’m looking around seeing their stuff strewn over the living room and thinking that they still look like a couple. The ex makes polite convo for a while then before he goes he says to HB “you still OK for that drink tmrw?” in a kind of uncertain tone, like he is not sure whether he should be asking or not. She nods back in an similar tone. He then went to bed and I started making out with her. After a while, she gets up and goes to the kitchen, then comes back and sits on a sofa away from me (just like the first date). I watch the film on TV for a bit, then figure I’ve had enough of her frigid crap and tell her I’m going.

I decide not to contact her until she contacts me and she hasn’t. As I’m writing this, I’m thinking why the hell do I even care? But it confuses me that she would talk to our communal friends as if we were a couple and she was giving off strong relationship vibes. Not to mention that I know she is very attracted to my looks. What concerns me is that maybe she was waiting for me to text her first, like I had done after all our dates and I blew it by being proud. But surely if she was interested, she would have taken the initiative? Or am I just rationalising??

One of my mates suggested that the ex said that on purpose to piss me off. But even if he did, what the fuck is she doing seeing him for drinks?

I saw her recently and briefly exchanged pleasantries. She seemed very shy and nervous around me. Mind you, she had trouble holding eye contact even at the best of times. I want to see her again, just to find out what the hell happened but am worried such a request may come off supplicative. I just wanna ask her straight out if she is fully over her ex. Like I probably should have in our first few dates.

She is a really sweet girl and I don’t mind taking things slowly but I was concerned that she was holding back purposely and we were heading to LJBF land and my value was decreasing.

I can think of several possibilities:

She was holding back intimacy because she is still on and off with her ex and has feelings for him .
She was setting the frame of her being the prize that I must chase after her and supplicate in order for a relationship to begin
She is just generally frigid

I just feel like I should explain why I didn't contact her. But surely if she was interested, she would have txted me?? yet I know she was strongly attracted to me. Wtf?!