I just returned from my camping trip at the music festival with my new-ish girlfriend.

We had a blast! It rained, and we dealt with it. We also put our tents up just fine. We got along well, and had no issues.

The only issue I personally had is she wants to cheat on her long-time partner. She already has cheated on him, a year and a half ago.

Well, at the festival, we ran into the guy she cheated with, and she was magnetically drawn to him.

Then at the end, we packed everything up and talked about the whole cheating thing. I told her it's wrong if she ventures in that direction again, and it seemed like she wanted to - like really wanted to. I told her she would be hurting her partner all over again and that's not right or fair to him. I talked again about an open relationship for her because she cannot be monogamous. She doesn't want an open relationship, she says. Well, sorry, honey, but you cannot have it both ways and her partner expects monogamy.

So, I planned on leaving at 5 PM, and she wanted to stay for the last band that started at 7 PM. She told me she would stay for the band, then drive home since her tent and all her belongings were packed in her car. Well, she told me as I was leaving that she would text me when she got home. She never texted. So I assume she stayed overnight, and I assume she slept with this other guy. I wrote her a message at 12:30 AM asking if she stayed. No reply.

It's not my business, but if she cheated on her partner yet again, I am kinda pissed. We talked a LOT about it, with me trying to instill morality into her by saying doesn't she care about how her partner feels? His feelings? She admitted to snuggling with this guy the night before, after I had already gone to bed. She also admitted that her partner would be upset over that alone.

I've met her partner and he doesn't deserve this - no one does. So I'm kinda upset with her, even though it's not my business. I feel like she lied to me and knew the whole day that she was going to spend the night with this other guy at the festival. So, I feel she was lying to me and to her partner.

And the day we had arrived? She was talking crap about this other guy, saying how awful and how dirty he looked. Yeah, right. She's deceptive because the very next day, she couldn't stay away from him and kept flirting with him.

I am convinced she cheated. Her tent was all packed up, so of course if she stayed overnight, she would have slept with this other guy in HIS tent.

This also upsets me because now I have to keep a secret from her partner as well. And I don't appreciate being brought into a huge lie like that.

She's cheated on every boyfriend, she told me.

So even though we had a great time together, I don't know how I feel towards her right now. I am not happy with her behavior and I think it's incredibly selfish and self serving behavior...

even as I was leaving and driving out, she said she would be "good". I have yet to hear from her.