You don't "put" him in to any "nice guy"-category.
Boyfriend destroyers are all about making the girl's boyfriend seem like a beta-male (Beta-male is the opposite of alpha male).
But this is easy, since the girl isn't in a relationship at all. To me it just seems like you have became her "personal psychiastric", but no worries mate!
When she tells you about her boyfriend leaving her and how it happened, you could just ask "Isn't that kind of bitchy?" which after she will, no matter what, answer "Yes.".
See? You didn't say anything, you just asked. She herself found an answer. Now say "I understand." and change the topic (P.S. just a hint, game her!

).
Also, "just hang out" with her at first, you don't need to make it a date if you want to meet her.