You met him after 18 months of separation and been together 6 months.
So the 2 year mark is now!
Has either filed for divorce yet? If not why not?
That’s what this is about! He committed to someone he was with for years only to split.
Separating is hard to deal with, divorce is a whole other ball game.
I am sorry but I think he will likely end things when divorce proceedings start. Because that is when he actually has to think about your relationship , how his relationship with her was 6 months in (likely just as lovely as yours)
You are in the honeymoon phase and he went through that with her too.
You might want to step back a bit emotionally.