There is no scientific evidence to support your claims here, not to mention that parent no longer being in love does not necessitate that there be an unhealthy dynamic in the home. People can be mature adults even in difficult and trying circumstances.

There are, however, numerous lifelong studies tracking the negative and traumatic impact divorce has on children. Besides that, we don't even know if they have children, but your concession to argue about it proves my point that it is a worthy consideration to have, one of many.

You don't know the OPs partner, their motivation or maturity level, and you certainly don't know what 'the right choice' is. How do you know OPs partner doesn't want therapy? Maybe they've been asking for it for years prior. You know absolutely nothing about them, yet you know what is right for them and their relationship, all from one quick glance at a Reddit post? Really? Are you joking?

I see red flags too, but I'm not arguing some delusional point that I know the only correct path forward for the OP. You are, and a petulant 'not sorry' doesn't really speak well for your arguement, either.