<human>: Things used to be great. I loved her. But it felt like she never put in the same level of effort that I did. I caught her doing some things that killed my trust.. Flirting with other guys and whatnot. (That's putting it lightly, I don't want to tell details) One time I caught her playing with herself while skyping a guy friend. Then recently she starts hanging out with this guy that I hate and she is super flirty with him. She won't make time for me, but she does for him. I can't trust her. I tried talking to her about it several times but she just gets defensive and won't be open with me about it. I know that you need trust for a relationship to work, but I loved her and I don't know what to do. I know the logical thing is to break things off. I already broke things off once but she came running back and said things would be different. But they aren't. Help me please because I am miserable.

Could you distill the essence of the text into 1-3 sentences?
<bot>: I love my gf, and I don't want to leave her, but she has lost all my trust and it's killing me.