Haha, even though I don't know too much about Boscolie, I can definitely see the parallels (with Boscolie also insisting they are just good friends for the longest time)! Although, I recently saw an interview with Bosco where he said he hadn't even thought about marriage yet because they're still working on their careers...while FengMi (especially YM lol) seem to be saying they really want a marriage/family (despite the fact that they have not yet found that "other person"...lol ).
I think with YM, she is very "cold" and "yu jie" if she doesn't like you (e.g. how she treated FSF at first, and also the way she was to that one guy on Happy Camp), but under usual circumstances she is quite friendly/professional, and to her good friends she will put everything out there for them. But you're right, despite the fact that YM has a very "open" personality, it seems like fans really don't know too much about her private life and thoughts...although I dunno about the singing--she doesn't strike me as someone who will do something she doesn't like just for the money (unless forced to by her company?). I do get the feeling that she enjoys singing and takes her album very seriously (she's said before that if she decides to do something, she wants to make sure she will do that to the best of her ability). But she's just not as talented singing-wise so can't expect her album to be that outstanding.
She's definitely still in a learning process with handling the media though--YM said before that she's already learned to be a lot more careful and reserved with reporters because they have taken a lot of her words out of context in the past (when she was more free with her words and would just say whatever she thought without realizing how it could be misconstrued). You're right, I don't think anyone can really get truly comfortably with the media...(especially considering how vicious some of them can be! Haha.)