[joshuamorton]

There's a correlation/causation issue here.

The GP pointed out that the relationship described in this has red flags because the relationship alone is the source of happiness. It would lead to a happier, possibly longer lived, less criminal person.

You seem to be implying (and I don't think this is intentional) that close personal and romantic relationships [for straight men] == a wife. But that doesn't necessarily need to be true. Maybe for romance, but certainly not for close personal friendships.

You're correct that a person isn't an island, but the focus on single romantic partner may be to the detriment of other forms of relationship which are still hugely valuable health wise.