He's married, to someone I know and like. I've heard bits and pieces from both of them over the years, suggesting that their relationship isn't great, but I always assumed these things crop up in a long marriage, and none of my business anyway.
I socialise with him quite a bit in a group. His wife is always invited, but often declines to come.
Recently, after many years, where I'd have sworn he was one of the good ones, never seen or heard anything inappropriate from him, he has decided to tell me "how he feels". I've really tried to shut it down and things will be normal for a while, but as soon as he has a drink , he's there declaring feelings again.
He's never suggested taking any action on these feelings, he still hasn't actually "done" anything, but obviously this is not OK.
In the last month or so, he's started messaging me, to the point that it's become almost daily. Nothing flirty, always positive. It will be things like "good so see James back a club last night" or "Sue did well in the comp at the weekend", "just checking, is it 3pm on Sat?", but this is all new. Previously these remarks would have been made in a group chat, if at all. I never reply quickly and only reply at all when an answer is required. I never make it chatty iyswim.
So, on the face of it all perfectly reasonable. If his DW were to share the messages on MN she'd be told it's perfectly OK for him to have female friends he shared an interest with. It's the sudden change, alongside the other conversations that bothers me.
I can't just cut him off, or at least not without sacrificing my main hobby and friendship group, and I'm not inclined to do that because a man is being ridiculous.
So what do I do?