Clue #1: Wife is nuts. And extremely jealous.
This... is where I'm going to open up a whole new world for likely most of you.
You see, I have a wonderful girlfriend, going back years. I've never had such a wonderful woman in my life... she loves me all sweaty, wrenching cars, building stuff... and loves me when I'm late for a date because I take so long to put on makeup. She's a doll. Here's the kicker:
She's married.
To someone else.
But it gets better. Her husband is my friend. We hang out, we go hiking, we build things. You see, my girlfriend and her husband have what you would call a "polyamorous" or "open" relationship. He has girlfriends too. And when I wish to date a new girl, I say "hey, I met this gal, gonna see how she works out."
I wanted to point this out because not all marriages are stuck in the monogamy paradigm. There's always a factor in monogamy -- jealousy. In non-monogamous relationships, that's not a problem. Openness and honesty replace the need for ownership and jealousy.
So... in this type of relationship, the answer to the OP is very different. In that case, the wife says, "Honey, you go have fun with your friend... I'll go hang with my boyfriend/girlfriend," or, "Honey, go have fun... just set a date so I can meet her before you do anything, okay? Muah! P.S. I'll be naked when you get home!"
Each couple sets their ground rules, but I obviously take exception to the notion that monogamy is a given.
The one and only sensible response in this thread.
Yes, indeed, people have interests that their spouses do not share. It makes me sad when friends of mine have gotten so sucked in to monogamous relationships that they're not even allowed to hang out with their friends, sharing interests that their wives do not care for. To me, this smacks of possessiveness, and a lack of love for a partner.
I can give one stellar example of marital caring: A couple I know... the husband likes the bondage scene, his wife does not. The wife simply lets him have a mistress he can see, and tie up, once a week. It makes them both happy.
Apologies for this post running so long... the gist is simple: jealousy is stupid. It does not solidify relationships; it destroys them. It's a flawed human emotion. And thus far, only the philosophers have gotten past it.