I dunno if its a manga thingy (like teenagers living alone) or is a japanese thingy, but i've never heard of a friend of mine which parents are divorced/widow that suddenly one of them remarries someone without my friend even knowing their parent was dating someone.
And yeah, she who is from the february is younger than him who is from may. And its even more absurd if you take into account they use the same calendar as the western countries.