I am female and in a relationship with a wonderful man.
I have an online friend, male and 10 years older than me, who lives on the other side of the planet and just seems to constantly message me day and night (note that our time zones are more or less opposite). He knows I am in a relationship and that I am happy in it, but from a comment here and there, I know he is attracted to me. I shut that conversation down very clearly from Day #1 and been very careful to leave no doubt about that not being even a remote possibility.
I have tried mentioning and talking about my partner in conversation with him at every opportunity, I delay hours in responding to his messages, being sure not to trigger the "read" flag, but it's just constant. The thing is, he's actually a nice guy and I don't think he's trying to hit on me, given I'm not single, 10 years younger than him and on the other side of the planet, there is absolutely no chance and he seems to have accepted that. I think he's just lonely and wants someone to talk to.
My partner is fully aware of the situation and knows he has nothing to worry about. I just want this guy to back off his messaging me all the time. Chatting from time to time is fine, but this is intrusive.
How can I get this friend to reduce the frequency of his messaging me without directly confronting him or hurting his feelings?
Notes and clarifications
I normally wait ages to respond, something the following day. The second I respond, he's all over me (sending me multiple messages and questions in a row)
When he messages me, he talks often about his girlfriend, how he is unhappy with her. Whenever he makes a comment like that, I always redirect the conversation to be about my partner or about working on his relationship with her. Sometimes about cooking, sometimes about work, but mostly just small talk.