Most of the class seem to know of Haruka (Molly's DnD and Manga club stuff has been at her cafe, and a few of the girls are insecure about her breasts which I wouldn't doubt gets around), her husband being gone is a given, given the space war, and Sensei is, well, Sensei, so it's likely more of an educated guess, overall.
Not sure if it's mentioned or not if you've declined Haruka in that timeline, though. If it's still mentioned, and he hasn't actually done it, then it's probably just for flavor.