The joke is the absurd and funny statement, "ladies, my wife is single (and you should date her (implied))". Basically they are best friends who broke up and now they are supporting the other dating by joking absurdity of the situation.

The link has extra panels and a comment from the artists that explains it more. This isn’t a joke so much as it is explaining their situation in a joking manner.

Amicable divorces are apparently funny?

I don't know. It's an odd one.

Comics don't have to have a joke, they can just tell a story. This is a nice story of two people who care for and support each other in spite of discovering their selves and life goals don't sync with continuing the original relationship. They manage to break up the romance with each feeling freed rather than dumped, so they can continue to be friends. Hopefully their eventual new partners will appreciate this.

Pretty sure it's that they were a lesbian couple but one realises they're a guy and the other realises they want kids so they break up but remain besties and try to set the other up

I'm not sure that I fully agree. I mean, to each their own etc., but what you're describing seems to be more suited for relationships without marriage. The whole idea of being married is that your discuss this stuff before your wedding and then don't just get separated because you "don't feel it anymore". The idea is that, if you feel like you drifted apart, that your work on that and don't just get out of that relationship on a whim. That's the promise you give. And even if you agree with your partner to just go separate ways (yeah yeah, consenting adults can do whatever the fuck they want, sure), a divorce has the significant chance to screw you financially for decades. I mean, I don't know how it is in the US, but I've seen too many people who got their finances completely fucked by partners that they consentingly parted ways with, who they swore would treat them fairly. Too many houses repossessed, too many careers ruined.

Is it okay to get separated? Sure. It's obviously also okay to remain close and support each other, of course. But this comic promotes a lighthearted approach to something that deserves a much more careful and serious take that I don't agree with. Those first few panels should have made them get counselling, not divorced.

Their mutual regard for one another transcends what they want from the relationship, which contrasts humourously with hetero norms of trying to change one other to get what you want

I was confused too, but the blog mentions his pronouns as he/him, so that's the interpretation I also arrived at.

Seems like it, they are announcing that the wife is single to the ladies after all.

I think if you're able to stay good friends with an ex-partner after a divorce, that's a good outcome.

Ending a relationship it's always, at least, a bit sad. But if that means that the people involved can continue to pursue happiness, and they can do that without resenting each other, that's cause of celebration.

"Several months ago" ... Not exactly suggesting it would happen over night. Recognizing a schism and supporting eachother through the changes in life is preferable to doing so depressed and hatefully, no?

Amicable divorces are narcissistic?