Colleague/friend suddenly became very cold on me

[Solonelyifeelsolonely]

It was always platonic, he's a guy I got on well with who's quite a bit younger than me and we used to talk very often, gave each other advice and so on.
Anyway we both joined a new department at the start of the year where there are many people closer to his age. Naturally the conversation dwindled a little from his side due to all these new faces he was getting to know, which I had anticipated.
However, we were both friends with another guy from our old department, and the friend in question still talks to this other man every day.
I know that the friend has spoken of mental health issues and taking medication for it (I also take anxiety medication).
Anyway, he's done a complete 360. Very cold, short replies. Devoid of any sense of humour.
Then once in a blue moon he'll be friendly.
However people are noticing it, we have a group work chat and he has snapped at me and one other woman on there for no apparent reason.

I'm racking my brains trying to think of something I may have done to offend or upset him but I can't. It does hurt a little when he's still constantly friendly with the man I mentioned up thread and a couple of others, but I've been frozen out.

I'll try to not take it personally. It does make me wary of mixing work and pleasure, I mean we're a large, friendly department where everyone gets on. I've stopped conversing directly with him now and we do work from home a lot luckily.

However I'll post something in the group chat that's unrelated to him and he'll reply with something that I can't tell is a joke or not. I actually took a screenshot and asked my other colleague if it was serious or not.

I shouldn't give it too much headspace however I'm hurt at the loss of the friendship and his behaviour concerns me. Not sure what else to do?

I think it's wise to be wary of mixing work and pleasure and good to have stopped conversing directly. Keep a professional distance from him to re-establish those boundaries and keep posts on the group chat innocuous for the time being until this phase passes. If you only moved departments at the start of the year, it's still early days there and you don't need any drama. Who knows why he's gone cold, seems most likely it's to do with him finding friends/colleagues he prefers in this dept, closer to his age, and not being mature enough to stay friendly with you too. Maybe he has issues with women. Whatever, it's his loss and him who'll look a dick if he's unprofessional about it. So don't give him any headspace if possible, it's great that you're not in the office together much, and this doesn't have to be an issue that clouds your day. It's a 180 by the way, not a 360, otherwise it would still be the same.

I did realise that afterwards about the 360, ah well 🤣
Yeah, you're right. I'm about 12 years older so it's not an enormous gap as such, but at his age I probably do seem ancient.
But yeah that's true, as long as I'm nice/professional with him then nobody can accuse me of anything.
I wouldn't mind at all if he just talked less as that happens, it's the snappy/bordering on rude replies. I'll just try to give him a wide berth.
He's already had a couple of warnings about his behaviour at work from management.

Maybe he thinks you’ve blabbed about the MH issues… maybe his meds aren’t working…. Maybe he’s a dick.

He told the whole table about his MH/meds so it wasn't just me, but otherwise I haven't told a soul. However I've noticed he was snappy with another woman so I shouldn't take it personally. I'll try to just put him out of my mind.