LOL, well...irregularity is one thing...being caught by “surprise” is something else.
I would think a woman would want to know around the time, give or take a few days, when she was due.
Some women who are very regular give a day or two of leeway, where those who are very irregular may give a week or two...:)
Being a guy, this was generally something opaque to a large degree, unless...it wasn’t!
“I would think a woman would want to know around the time, give or take a few days, when she was due.”
Definitely ... a woman would WANT to know. Sadly, nature often doesn’t cooperate. First miss a couple months, then multiple in one month. Impossible for planning.