Why would she tell me this (girls only)?

So my friend, who I kinda like, has this boyfriend she says she really likes him and cares a lot about him but she also complains to me about him being moody and whiny. The other day however she told me out of the blue that he cant get her wet she also mentioned how she said if one of them were to cheat on the other she thinks it would be her. She also told me if anyine was to cheat on the other it would be her. Why would she tell me that we don't really talk about sexual stuff and since then she's been trying to get me to go to the gym with her and stuff