@annythinkstoomucj Autism aside, just make sure you’re sure about it.
Has it been enough time? I assume you plan on easing him into a more serious and stable role in your sons life based on your sons acceptance of him. I think that would be the best course of action in my opinion. Please remember that it will take time for bonding to occur, and if it doesn’t work out, it will be difficult on your partner as well.
I went through this recently (she has 3 kids. None with autism, but I got close to the kids. They’re fucking awesome actually.) and to be honest, it was like dumped twice. Once by her, and once by the kids. It really sucked/sucks. It came out of nowhere too.
Just be mindful even when your mind is full, because these scenarios can fill up your plates quickly, and things can get intense out of nowhere. Just remember that this can hurt your partner a great deal as well. Best of luck!