Tbh, I have zero interest in being friends with couples (unless they’re family of course & that’s different!). All they’ll talk about at the dinner table is their kids & I don’t have any kids myself so it would just be a boring conversation!
Couples usually invite other couples to dinner because the moms meet up at their kids’ school & get to know each other. It’s all about having things in common. I really don’t believe it’s an intentional exclusion of singles from the social circle of couples. Would you invite a married couple to a single girls’ get together? Hell no! 😁