I need some help (sorry for the long post)

Me and this guy had been friends for years and then I think the feelings changed and it was mutual. We went on a couples date, we had a great time, he kept saying how much he liked it and we should hang out again soon and then he stopped answering my texts... I asked if everything was fine or if I had done something wrong and no response... my birthday come and he texted me a day later with a sweet message and apologizing for not texting me back and then we didn't text back again... a couple months later his birthday come and I text, we thanked me and then stoped texting. I just dont understand, did I do something wrong? That's what I want to know... I know he is going through a hard time (because we have friends in common but he never said anything to me)

I cant seem to find closure over this. Should I try and send one last text really trying to understand what happen or should I just not do it? My mind says that I shouldnt but the heart wants what it wants... any advice?