Ok I made an account specifically to post here and find this one yuri. I read it a couple weeks ago I think. The premise is an office worker, her old friend who is trying to become a writer, and a seamstress with the same name as the old friend, wind up living together and a love-triangle and eventually polyamory ensues. I remember tons of tiny details about this work but nothing in the Love Triangle tags, Polyamory tags, Office Lady tags fit from what I can find.
Tiny details; the manga opens with the third woman, the seamstress, being pushed/stumbling down the stairs of a train station and accidentally ripping the MC's coat sleeve, which she then promises to fix, and does. The seamstress has an abusive ex who calls a lot and comes banging on her door the first time the MC visits her apartment. There's a lot of stuff about schedules and when the various people are in and out, and when two of them are alone and whatever. The MC works at a company whose boss wants to start a chocolate business, and she knows nothing about chocolates so she takes it to the other two girls who help out, and the author/childhood friend winds up becoming close with the boss. There's a vacation arc with the three of them, with a bunch of time about the MC trying to convince the seamstress to marry her so they could have a vacation together, and yes I've checked everything in the "Beach" tags for those chapters to no avail. There's a couple different arcs of the different girls leaving the apartment they shared "for good", before eventually returning.
There's a wedding scene where the seamstress fails to show up and the MC winds up having a ceremony with the author friend, and then both of them go find the seamstress together with leftovers. The final chapter is the MC on the island where they took a vacation to talking about getting her boating license and telling one of the locals that both of the other characters are her wives, and he makes a joke about it.
Lots of sex also happens, at first just between the MC and the seamstress but eventually between the MC and the author friend as well. I think it was like, mid 2010s but it could've been early 2020s, pretty old-school art style for sure.
I have searched everywhere and I /cannot/ find this fucking series, so if y'all happen to know it I'd love to know. Been a rough week and a bright point would be greatly appreciated. Thanks Dynasty community <3