Question: I was fixing a button to a jacket that fell off on Shabbos, though my husband said that I shouldn’t be doing this on Motzaei Shabbos. Why is this?
Answer: The Gemara (Pesachim 50b) writes that one who does work on Motzaei Shabbos will not be blessed. Based on this, the Magen Avraham (OC 299:15) quotes the Abudraham (end of Seder Motzaei Shabbos) who writes that the custom is for women not to perform melacha on Motzaei Shabbos.
The Aruch Hashulchan (OC 299:22), however, writes that this custom is unheard of, and providing that they have heard havdala, can do any melacha. He quotes the Gemara Yerushalmi (Pesachim 4:1) that writes that while there is a minhag for women not to do menial melacha on rosh chodesh, there is no such minhag to abstain on Motzaei Shabbos. As for the Gemara that writes about lack of blessing, that is specifically talking about doing melacha before hearing havdala.Likewise, R’ Ephraim Greenblatt (Rivevos Ephraim 2:107) writes that as this minhag is not brought in the later poskim, women may do any melacha after havdala.