Say you aren't interested in leaving but you know he does not want to be married.

You move on and try to have kids. To avoid looks you want to get a ring and plan on buying it for yourself.

What year in a relationship would make you consider doing so?

And yes I know you chose to be with him so just be happy blah blah blah, but let's be honest, the first thing people do when they see a pregnant woman is check her left hand. So buying yourself a ring to not be embarrassed.