My friend's step father suddenly passed away this Monday. I used to be very close with this friend, but haven't really talked to him in the past few months. If I send him a message on Facebook, sometimes he gets back to me and sometimes he ignores me, so I'm not sure where we stand right now. But I've known him for about 12 years, we've dated briefly, we're in a band together, and he used to be one of my best friends. I know I annoy him sometimes (unintentionally) but I just don't know why he's been ignoring me. When I've asked him, he says he's been busy- but we went from talking almost every day to only maybe once or twice a month. We haven't really had any fights, though we have been recording and just released a single, and that's been stressful and there've been some disagreements in the band.
He hasn't told me that his step father died. I saw that he and his mom posted an obituary on Facebook.
Yesterday was my birthday. His mom posted a nice message on my Facebook page.
My question is: should I just say "thank you" like I have for most of the other messages, or should I add something like "I hope you're doing well" or "I'm sorry for your loss?" I haven't talked to either of them in awhile and neither of them have mentioned anything to me about the death. And I'm not sure if I should bring sadness into a post that's supposed to be happy.