I'm sure that when they invite you, your spouse is also invited. If you have a child, perhaps you can find a baby-sitter. If it's the kind of event where kids can come, then bring them!
To be honest, though, if the shoe were on the other foot. I would find your "superficial" hellos to be a disguised middle finger. True friends don't just say hello when passing each other. They hang out and talk in the lunch room, they gripe about profs and reading assignment after class, etc. Ppl say hello to me all of the time but I know who my real friends are and several of those ppl aren't included.