Had a guy move in last summer. I'm currently 31, he's 29. He was a totally normal person the first several months we lived together. He had friends, a girlfriend, hobbies, etc, and though we were different people, we talked some here and there. Then, probably around mid September 2019, something changed where he very suddenly became super reclusive, stopped talking to me and started avoiding me, broke up with his girlfriend (who he talked about marrying just weeks before and she was totally blindsided herself), and started staying in his room with the door shut ~100% of the time. He does not use our kitchen and only comes out a couple times per day to go to the bathroom or answer the door quickly to grab food he ordered (usually a sandwich or a pizza). Any time I try to talk to him during these very brief moments he appears, he gives me like one word responses and does not pause for even a split second to try to make conversation of any kind.
He is in the Navy and has already served 4 years. He told me when he moved in that he decided he wanted to become an officer which required a 4 year degree, so that's why he moved here and is attending school full-time on the military's dime. Before covid, he was still extremely reclusive, but I didn't worry too much because I figured he's at least going to class and his ROTC thing, but once covid hit, everything is online, and he no longer even leaves our apartment. I work full-time, so I can't say for certain, but from what I can tell, he has had no in-person human interaction (besides answering the door to grab delivery food and seeing me maybe 1 minute per week if that) for MONTHS now. He stays in his room and plays video games online; I can hear that. What else he does in there I do not know.
Anyway, while I'm normally one to very much mind my own business, I'm starting to get a little freaked out. He has never said or done anything that suggests he's violent or plotting anything, but going months without interacting with humans and being clearly depressed for months is not healthy and often leads to pretty extreme dysfunctional thinking and behavior. Again, he's never SAID anything explicitly worrying, but at the same time it wouldn't surprise me at all if I came home to find him dead one day, not to mention the possibility he might snap in some other way.
I'm kind of at a loss as to what to do since I've already tried "reaching out" to him numerous times over the last 6 months, and he clearly does not want to talk at all. I've thought about trying to contact ROTC or whatever and have a meeting with someone and explain what's going on, mainly as concern for my roommate but also for my own safety. Not really sure what else to do, if anything.
Any ideas? Am I overreacting? All input is welcome.