My life would have been a disaster on steroids if I’d married my college BF (I ran into his parents a while back– quite by accident, we live in different parts of the country– and got the entire download. Including the fact that as I was planning one kid’s wedding, he was celebrating the birth of a new baby…. I lost count as to how many babies with how many ex-wives…. ).
So I get your reluctance. People change and that’s ok. I’m not sure if your kid can manage the research supervisor piece, but if it were me I’d just make sure that down the road, your son doesn’t feel locked in to this relationship because of her dad. That sounds to me like a bad Victorian novel in the making- or at least the worst episode of “Sex in the City” ever made.