I still find it heartily amusing that the youngest one is the one regularly getting laid, while the rest are either just barely at the smoochin' stage, or just flailing around about their crushes, in order of youngest to eldest. I mean I'm sure that that's the author's intent but I dig it anyway.
Because the Elder one is in couple with her own student and so want to do it after she graduate. The second one is not even in couple with her boss and the third one just starting to going out.
... yes... I am aware...? And..? Two eldest are flailing around--eldest has flailed because she has to wait till her gf graduates when gf keeps putting on pressure, 2nd eldest because she has a hardcore crush on her boss--and 2nd youngest is just naively flailing because naive. Doesn't change what I said ...