I hear you. Separate vacations are not my concept of marriage.
Of course not! They are not mine either. But, right now, H is not "in" a marriage mentally. H needs to understand that this is what's going to happen more and more often should he continue on this path. It's a good thing to leave the WAS alone with their thoughts while they know you're out having fun! Makes them think: is this REALLY what I want?
We had a vacation planned last year for all of us. The date cam closer and closer and finally W said she wouldn't/couldn't go with me and to just leave the boys with her. I said that if she didn't want to go, it shouldn't cause anybody else to miss out on the trip, so I took the boys with me by myself. I think it may have been too early in the sitch for this to cause a radical change in W, but it did felt like she came a little closer again.
Regarding to geting him to go see a dr., it's the same difficulty as getting a WAS to go see a MC. It's gonna be tough not coming across as wanting to "fix" your WAS. If you decide to enlist friends, be very careful with that! They cannot under any circumstance even give a shimmer of having you talk to them about something even remote to that. Any remote feeling on H's part of you influencing your friends for that purpose will come across very negatively. Trust me, I learned the hard way! Just wanted to make sure you're warned.
In the mean time, try to have a great time on vacation!
