I don't know if this was already suggested (there was lots of text and I will go read it later, because it's an interesting topic)
Any chance he can look for somebody to date who is where his job is? If it's OK for him to have overnights at some point, that might be sensible, he could get right to a meeting/date after work. Early on it could mean getting home very late, but with the happy dating feelings it might not be too much of a problem. If it got serious and he could spend a night every week or two, then he'd be close to work in the morning and he wouldn't feel so rushed that day so perhaps he'd have a bit more energy the rest of the week.
It might make him feel like he had extra time with the new partner (that he wouldn't have if they were right by you guys, he wouldn't be extra tired from work + commute) so wouldn't feel the crush to see them as frequently with the NRE craze. It might not have such a stress effect on the home life if it was either Sundays/work nights that he was that far away.
Don't know how the kids would be affected by it, but if it wasn't too often, that might be a helpful way for him to have his cake and eat it too, while taking a bit of stress off the dating/commute issue.
Happiness will never come to those who fail to appreciate what they already have.