I think my own, personal old fashioned beliefs came in unill you reminded me; you don't have to be married either in sims or in real life to have relationships with another. I'm no prude for others (same sex, live together, whatever it's a person's choice and I will support it for them) but for me, not others, there is no ifs, ands or buts, marriage first.
So, that is what was stuck in my mind, they were no longer married, so no longer whoohoo. So when it had popped up; it didn't click in my brain sims setup, not my personal ones.
Okay, back on topic, they are able to not only marry, but she would be able to have a child. Interesting, may try that sometime. Side note, she died so I get to have fun watching and seeing how they interact with each other. Another couple I will try the having a baby and maybe bringing them back to life.