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

My best friend (F22) cheated on her boyfriend(M27) repeatedly over a one month period while she was away on holidays.  She says that her and her bf were not "official" yet.  Now they have been dating for about 9 months and in those months, they include the month she was away, and cheating A LOT.  

I can't help but feel really judgmental about this because he really really cares for her yet their relationship is based on lies and cheating. 

I have never been cheated on, nor have I cheated, but I sure do hate cheaters.  I also have never said anything to her other than, "Are you going to tell him you cheated?" But of course she doesn't want to.  Their relationship is getting a lot more serious these days and I just would hate to be her boyfriend.

I can't help but be seriously bothered by this.  What is going on with me?  I try really hard to not think about it but I can't stop judging her.  As a best friend, should I push her in the right direction, or just stop judging her and support her in whatever she pleases?
<bot>: Very bothered that my best friend cheated on her boyfriend.  As a friend, should I support her no matter what, or tell her to try to do the right thing...?