<human>: Can you succinctly summarize the text in 1-3 sentences?

First some background. I have been with my girlfriend for almost 2 years now. Our relationship, like most, started off perfectly. We like a lot of the same stuff and we are basically best friends.  Fast forward about 6 months. Girlfriend decides to get some birth control for the first time. Her sex drive literally dies and so decides to get off it. Her drive has been dead ever since. Go forward now to 1 year and 6 months into our relationship. I think everything is going ok. I mean I have sex once a month if im lucky. So the lack of sex has led to some issues, but we talked and it was fine.  Then come about 1 year and 6 months into the relationship. hanging out with the GF when she says out of the blue she wants to go on a "break". Her reasoning is that I am "too comfortable" in the relationship and I do not try.  I have been on "break" with her now for about 6 months. She acts no differently than when we were together, so wtf the break is I have no idea.  She goes out a lot with her sorority as well. She even admitted telling me that she "likes getting compliments from guys." She went to visit her family in mexico, and while there hung out with some guy for the 1 month she was gone.  Here is her ending message to him after she left. "im sorry. I hope you had a safe flight home. and i really enjoyed meeting you and wish i could have gotten to know you better. I really like you. do not change. Maybe ill see you again one day." Her saying sorry was because he said he was mad at her.  Now that she is back she is acting really lovey dovey and I have no idea what to think. My friends say she is probably cheating on me and that the "break" is basically an excuse. I honestly have no clue and I am so lost. I love her to death, but I feel like this relationship is in fact falling apart.  Thoughts?
<bot>: GF says she wants to go on "break", we havn't had sex in ever, and she likes to flirt with other guys.