<human>: So I've been off and on with my girl for almost a year now. I love her to death but tonight she implied she wanted t break up with me. 

After trying to get her to talk to me in person and her refusing, we agree to just go to bed and talk about it tomorrow. Obviously I'm not asleep and probably won't be seeing as I was asleep for 18hours today. But in the end she was saying:
       "I'm just not happy with you. Its nothing you've done wrong or are doing wrong, I just don't want to be with you."

Now, I can understand if she honestly felt that way, but I feel like something else is going on. She's had a past too. She's openly admitted to cheating in me 1.5 times. The .5 is from her trying to test a guy to see how faithful he was but he ended up leaving. Than she cheated on me fully from having a friend come over who spent the night. She told me she never intended for it to happen but it did and she didn't do anything to stop it.

I've talked to both of these people in person and ensured they don't see her again.

After learning all of this, I still put my love for her above it all and decided to stay with her. Now she's hanging out with this new guy, Eben. He spent the night and when I came over to se her, she told me they slept in the same bed and when she woke up, his arm was around her waist and he was complimenting on how soft her skin was. 

This bothered me immensely. So she gave me her phone and I told him to lay off. "I don't mind yall hanging out but I'm very protective of my girl." So I brushed it off because she said nothing other than that happened. But now after sleeping for 18 hours, roughly 48 hours after that talk, she tells me she isn't happy with me and that she doesn't want to be with me. 

Now I'm just waiting for tomorrow and my chance to talk with her and hope we can figure this out.

Can you summarize the given text in a few sentences?
<bot>: girls, when you say "I'm not happy anymore" what's your reasoning behind it? Because i don't think you just drop out of being happy.