Oh J, I am so sorry to hear this, although I am not so surprised. You have truly taken the effort to listen to your girls and take a slow pace. ANd I am going to be 100% honest with you. You can go even slower and give even more time, but it's not going to change until these kids are grown and more on their own,rather than their parents. Having kids become siblings who aren;t actually their siblings is super hard. I think one reason I really wanted it to work with M is because our kids got along famously. ANd I know how difficult that is to find. We were so lucky in that sense.
If you and the doc truly love each other, living together apart as you are is probably the best bet. You live 5 minutes away from each other, have enough money to maintain your own households and get to see eachother often. You could even get married when living in 2 different houses if that ring on the finger is that important to her. When your kids are way older, then maybe moving in together will be more feasible. you can do somethings together and some things apart. Unfortunately, the doc focused more on learning bible verses and spanish, rather than social skills. Maybe in the next few years he will grow up a bit. Then you can consider sharing households. But I don't see it happening anytime soon, But it doesn't mean it has to be the end for you and the doc. If you really have something special, you will both recognize that your relationship will have to look different.
I know for my daughter, the one very important thing for her is not moving out of her school district. ANd if a guys residency is what determines where his kid goes to school and neither of us wanted to move for our kids sake, we would have to be ok with living seperately for our kids for a few years. I do know an OG DB'er who has been with his GF for maybe 4 years now? they have the school district issue, so they have a great R, but aren't living together.
Truth be told, relationships with kids post divorce look so much different. It's a new norm I guess.
I trust things will work out the way they are supposed to for you. I really do.