I’m male, a gamer, and in my forties. I have done what your SO has done, and it wasn’t for nefarious purposes.
Online culture is weird and sometimes a bit of a minefield. Many of the female gamers I’ve played with on recurring servers have, over time, indicated that they are or have been suicidal. Some thrive on the attention that comes from working together in a game towards a common goal.
Some react very badly to any change from the people they play with.
So no, I don’t usually tell people I play with about my relationships or other identifying details of my personal life. There’s far too many people who are creepers, stalkers, obsessive, or have real issues understanding personal boundaries.
Yes, we can chat about mundane personal things or the news or whatever, yes we could meet up and have dinner or something, but I’m not going to let my possibly incorrect assessment about you affect the other people in my life.
You know your SO well enough to judge if he’s doing something shady, but don’t mistake an online relationship with a real life one. Maintaining the status quo isn’t only to get topless photos.