Backstory

I've had this one girl I've been seeing since September. We were never exclusive, and she knows I have sex with other girls when I want to. I was also hooking up with a former oneitis for a few weeks in January/February, mostly because I liked how the tables had turned since TRP.

Now the girl I was seeing seems really sweet. I always knew she was a branch swinger because she was still in a relationship when I met her, but I was OK with that. She's new in the city, and doesn't have any friends/ways to make friends her own age. As a result, she uses tinder to meet guys to go on dates with, and claimed that she didn't hook up with them beyond kissing when she felt she had to.

She texts me a few times a day and I mostly ignore her. She calls me most nights and I’ll have a brief chat with her before she goes to bed. She loves me, I tell her I love her occasionally, but I never initiate it and ratio is like 1:3.

The Other Night

We were hanging out and I asked if she had had sex with anyone else since we met. She admitted she had had sex with a guy in from her hometown over Christmas break. We were texting/speaking occasionally while she was gone, but I mostly ignored her. From the sounds of it, it was a nice guy who had a crush on her in high school. She initiated it. I don't care that much about this in itself, but that she lied about it at the time.

I was suspicious, so while she was doing my dishes I opened her phone and scrolled through her texts, lots of conversations with other guys making plans etc., which I expected, but one caught me by surprise. Before she had told me about a guy she found really hot, and who she went on a date with a few weeks ago, but he didn't want to go on another date with her. I found this guy on fb, solid 10/10 for the city, whereas I'd say I'm more of an 8.5 for the city.

Anyway, based on the texts I see they went out pretty recently, and I suspect she stayed the night (she lives outside the city, busses stop at 10pm).

So we chat for a bit, and I ask her if there's anything she needs to tell me. She's upfront about all of the guys, and what she says confirms what I know from her texts. Then I ask about the 10, and she says she went on a date with him. I ask if it was once or twice, she admits it was twice. I ask when, she says awhile ago, but acts like she can't remember, then she comes clean and says recently. I find out where they went etc, and she admits to going to the bar, and trickles out that she went to his place. She claims she tried to hook up with him, but he wasn't down, so she called a cab and left. I have no direct evidence she's lying about this, but I suspect otherwise. She goes to shower, and when she comes out I ask if there's anything else she should tell me.

She admits she gave some other guy a handjob a few weeks ago, because she felt obligated (he's been sniffing around since October, taking her out etc.). I can't be too mad, because she knows I was fucking my former oneitis that night (was trying to make her into a plate, didn't work).

I go back to talking about the 10, and ask if she stayed over. She says she didn't, I ask if she cabbed, she says she did, I ask if she called the cab (yes), and then I ask to see her phone record, and she freezes. Admits to staying over, trying to fuck the guy, but he wasn't interested. He does seem like a standup guy, he's probably 5 years older than me, and I'm 5 years older than her, so he may have felt weird about the age gap, or maybe he only fucks hotter girls, or who knows what. I'm not really sure if they had sex, but at this point I don't care. She really wanted to fuck him, and a few days later invited him over and he didn't respond. In my mind, she's found someone she's more attracted to than me, and that's what bothered me.

Going Forward

Upon learning all this I go a bit cold. She's stuck at my place for the day, so I ignore her and tell her to read while I study etc. She's really upset etc. etc., before this she was always saying how much she loved me, I'd humor her, and in many ways she was my girlfriend.

Keep in mind, throughout this thing I've always said she could do whatever she wants with other guys, I didn't set any boundaries, although I said if she hooked up with anyone I'd reconsider our relationship. I'm in a professional program, and exams are coming up. Also, I've slacked in other ways lately, I don't lift as much as I used to, and I've been eating like crap. I also started being more affectionate with her, and treating her nicely.

I can accept that there will be other guys she will find more attractive. I don't have an income yet, I'm not shredded, although I am strong and tall (6'2), I get girls but I'm not beautiful or anything. So her getting tingles from someone else is inevitable.

I fucked her that night, having never had make-up sex I didn't realize how much harder girls work when they're trying to regain your trust/affection. I think I'll keep her around until she leaves town in a few months. I'm not sure whether to set hard boundaries for her, or give her a firm demotion and risk her thinking its hopeless and moving on. In my mind she is demoted for sure, but I feel I can get more out of her if she thinks she can win me back.

As a final note, I don't blame her for anything. If a guy isn't committing she should be getting other guys to take her on dates, and if a better alpha comes along she's allowed to try for him if she's not committed to anyone. I'm taking it as a learning experience, and will be careful not to let my guard down again- no matter how much a girl professes to love you.

TLDR: Got Complacent, main plate got tingles for better guy, probably fucked him, now she wants to earn my trust again- not sure whether to string her along or hard demotion.

Edit: Thanks for all of your comments.

I was wrong to describe her as a plate. She's a girl I've been dating since september, but under the pretense that I'm allowed to sleep with other girls, and she's allowed to go on dates with other guys. I was OK with her collecting orbiters who took her out to dinner and entertained her while I was busy with my professional/social life, and she'd often come over to mine to sleep over afterwards. I didn't expect her to sleep with anyone else, and wasn't sure how to react when I found that out. While no clear boundaries were set, the general idea was I wouldn't take girls on dates or do much more than drunk hookups, while she wouldn't fuck anyone else.

I violated this fuzzy boundary when my former oneitis really wanted to hang out with me, and I started sleeping with her and hanging out with her. This was done largely to restore the damage she did to my repuation when I got pissy and made an ass of myself last year. By fucking her and having her beg me to date her it made my conduct last year look less one-sided. I didn't go into details, but my "main plate" knew what was going on.

I was surprised that she was trying to fuck someone else, but I guess I shouldn't have been.