How can you cheat on someone you claim to love?

I just heard about Kristen Stewart cheating on Robert Pattinson yesterday and I can't believe that she did that!! I mean ok I get it sometimes people do stupid things, even celebs they are only human too..but when you are with someone that you love? How can you do that?

If I was with someone that I loved, I have been before and I didn't cheat on them, no reason too!! I am with the one that I love then why do something stupid that you will regret later??
I just don't get it..I feel bad for him...they are such a cute couple and I really thought that they had chemistry in the twilight movies and that is what made me love them both but now this..ridiculous! 

And especially her being a celeb, did she not think that it would come out? Did she really think that someone wouldn't be following her and get pics somehow?? Crazy!

Just my opinion...