Is it normal i think my partner had a psychotic episode?

My boyfriend of 5 years has recently been having some mental upsets. He's 21 and has always been a straight edge, maybe a little tightly wound, but he's a genuinely good guy. The other night he started going on about how he thinks "something is trying to communicate with [him]" and then proceeded to get really really upset over it, and he isn't one to show weakness. It really alarmed me because it was so out of the blue so I fought him on it for a bit before just giving in and agreeing, then trying to distract him with a game of basketball.

He's been going on about "aliens" and you can really see the fear in his face when he talks about them. I'm really worried, I've been spending a few nights at his apartment with him and his roommates to make sure everything is going smoothly, which it isn't. He's in training for the Marines and I don't know whether I should try to convince him to hold off a bit and see how he feels later.

He's just been so disoriented and dissociative lately. We've been together so long and know each other so well we don't really harp on the obsessive early dating super mushy attitude, but for whatever reason he keeps wanting to validate our relationship. Like he's calling me boyfriend all day or dressing up nice to see me and getting jealous over my friends. And I just have to remind him, "Yeah, bud, I'm your man, now get your pajama pants on and stop being so mushy romantic"

It's just, we've worked hard for this level of comfort and confidence in our relationship, and now he seems to be looking at me like he just fell in love with me. I tried talking to his mom to see if he ever acted like this before and she was no help. The aliens are freaking me out, he genuinely thinks aliens are trying to talk to him and that if I don't recognize them I'll "get left behind"

TL;DR - My boyfriend is acting like he just met me and just fell in love with me and he thinks aliens are trying to talk to him.