Straight people are so confusing sometimes. They spend countless hours of their precious time on God's green earth debating whether men and women can just be friends. Even though iconic movies like When Harry Met Sally tell you, "No, this man and woman cannot just be friends," I'm all for a mixed-gender friend group. If you can't trust your partner to not fling themselves at any person of the opposite sex that they like to spend time with socially, then what can you trust them with?
Everybody has been in a situation where a friend starts ignoring them because of their new boyfriend or girlfriend. It's clear that their relationship is more important than maintaining their friendship until they break up and inevitably come crawling back to you. That's infuriating, but almost less infuriating than being explicitly cut off by your friend because their partner is too jealous to handle them having other human relationships outside of theirs.