If she starts to speak about even one problem, was it a relationship or easily fixable, I either change the topic immediatily or see what she has to say and then just reply "I understand." and change the topic. I ain't her psychiastric

!
But take merch's advice to the heart about giving LJBF to
them (the girls). Actually I say LJBF to all the girls I meet... Love it!
P.S. Don't get me wrong here. If you tell them "LJBF", it does
not mean that you have to
really LJBF with them.
And I wouldn't kiss the ground infront of her boyfriend either, with all that "He is a really really really really etc..., nice guy"-stuff.
All that BF destroyer really is, is making her BF look like a
beta male. Not YOU looking like a beta-male adoring HER boyfriend... Oh god... Remember, you are trying to get the girl, not the boyfriend!
You can do it just by saying "So, how is it like to be in a perfect relationship?", this will get her to think everything that isn't good. Add good gaming from your part to this = success, bravo!