<human>: Can you condense the text into a few key points?

After more than a year of dating, I was feeling constrained in our relationship, and seeing as I had had very little sexual experience other than what I had with my girlfriend, I felt like I was too young and inexperienced to be committing to being in a such a serious relationship with this girl. So I broke up with her. While we were broken up, I had sex with another girl.

We recently got back together, and I know now that I love her more than anything and want to spend the rest of my life with her. The problem is that she took the fact that I had sex with another girl very hard. I'm the only person she's ever had sex with, and she has said to me that she doesn't think that it's fair that she's now meant to be expected to live out our relationship having only ever had sex with just me.

In response to this I say things to the effect of, "That is a perfectly valid way to feel, and if you think you can't stay with me because of this then you need to break up with me. It's not right to stay with me half-heartedly because you feel like you want to fuck someone else."

But she always chooses to stay with me.

She brings up the fact that I've slept with someone else every once in a while, in a very hostile way (e.g. "I CAN'T BELIEVE YOU FUCKED SOMEONE ELSE WHILE WE WERE BROKEN UP").
The way I see it, she either needs to let it go and stay with me and stop holding it against me like a grudge, or she needs to end things with me and move on.

I feel like this is just an affair waiting to happen.
<bot>: Had sex with another girl while my girlfriend and I were broken up. We're now back together, but she took it very hard and feels like she needs to experience sleeping with someone else.