Sounds like a really good man.
When I met my wife, Jacob - her son - was about a year old. His dad was pretty much out of the picture, didn't want to see him, didn't want to take him for visits, that type of thing. He did pay child support. Well, after Cindy and I got married, after about two years of dating, I contacted Jacob's dad and asked if I could adopt Jacob. I told him that he would then not have to pay child support, or cover Jacob on insurance, and that I would never stop the two from seeing each other or being together. He thought about it, and finally said no, so Jacob is still my step son. Jacob has always called me Dad, and his real dad is his "Bruce Dad". Cindy and I have never asked him to call me Dad, he has always done it on his own. Jacob is my son just like his brothers.