A woman who davened Maariv on motzoi Shabbos and omitted Havdalah in her tefilla, and subsequently ate prior to Havdalah on wine, is she mechuyev to repeat her SE?
In my opinion, there are 2 reasons to be meikel and not require to daven again:
(1) She was not required to daven Maariv in the first place.
(2) There is an opinion in the Shulchan Aruch that noshim are potur from Havdalah (even though this is not the accepted psak).
So I would say safek brachos l’hakel.
See Piskei Teshuvos 294-3, ftnt. 23, he talks about your question, and he says that if she usually davens maariv she has to daven again.