when you date someone with kids you do enter into a more complicated world of exes, commitments, etc - its not as simple as two single people without kids dating..I'm not saying its bad but it is a fact of life when you date people with kids...
When I met DH we were both 24. We're just 3 months apart in age. We were worlds apart in lifestyle because I had two kids, friends who were married and also parents, etc. and he was childless with friends who were single and childless.
We discussed the situation and DH was well aware that my ex was NOT going to help with the kids in any way, financially or otherwise. He'd already thought about it and accepted that being with me would mean becoming an instant father.
His friends thought he was absolutely insane for dating and getting serious with a woman who had kids.
I think the hardest thing for him was not being able to just go do something at a moment's notice. He missed many social events because we couldn't get a sitter and the event wasn't child friendly. Missed many others because we got such short notice there wasn't time to gather up the kids, get everyone ready, get the kid gear packed and stowed in the car, let the dog out, and get there before it was damn near over.
He drifted away from most of his friends. He was too busy working and raising a family while they were footloose and fancy free. Now that the kids are older, he tried to reconnect. Unfortunately, they are now in the thick of raising younger kids and are too busy.
We won't even get into the stuff he wanted to buy, do, or see that we couldn't afford because kids are expensive lil critters. There was a lot that he wanted to do we could have done if it was just the two of us, but wasn't a great idea or too expensive to do with kids.
And, of course, kids are cute. We're programmed to love them and think they're adorable so that we don't kill em. This means that the person stepping in to raise someone else's kid is going to get attached. Eventually, they'll probably even love the kid(s). So, what then? What if it doesn't work out? Now they have an attachment to kids that they have no legal rights to should they split before marriage or get a divorce.
There really is a lot more to consider when dating someone with kids that isn't even on the radar when dating someone without kids.
Which kind of brings us back to the OP. It seems he and the boy get along wonderfully and care very much for each other. It also seems that the OP and the boy's mother are a bad match and wouldn't have a good marriage.
I agree with many others. She's not ready for a marriage or she's not compatible with the OP. Maybe both. So, OP, I also advise going through with ending the relationship.