I'm going to be controversial and say that if you think she's in a really s*** place, you should help. If someone's thinking of dangling themselves from a rope, helping them comes before your f*** buddy relationship.
Doesn't matter if someone is male or female, f*ck buddy or GF, if they're close to you in some way it's natural to help them out.
In fact I'd say from personal experience that the girls I helped out with problems in their personal lives usually developed a stronger attraction to me afterwards. It shows you're not a d*uche, and even if you just want sex with this person, there is nothing wrong with caring about their well-being...quite the opposite.
Just once the worst times are over, don't become her disposable emotional tissue. Offer her some light support through the tough stuff, if she wants it that's good...if not, carry on as normal.
My 2 cents anyway.