Could be (ulterior motives)--but until you get to know someone--try to assume not. Not trying to be judgemental (I really hate when people are judgemental) but it really can help to PM people at PC. This answer makes me feel like you are not doing well. I know you have a really strained marriage and understand how awful this can be.

"How are you doing" is a bit like "Hello" and "Goodbye" a standard opening to a conversation but the answerer can just say, "Fine, how are you?" regardless of how they feel and move on and just listen if they are not in the mood to "spill" their feelings....