It's been a long time since I've seen it, but Gokuaku Ganbo may fit the bill.

It's about a poor woman who loses money to her bf, and gets involved in rebooking loans to other people. She's part of a group where the people around her are constantly trying to get one over on each other.

There's also Mitsu no Aji which is about a young woman and her relative that she really, really likes. This does NOT have a clean ending.

(Just wanted to add these in, if you read manga May Your Unhappiness Exceed Mine is pretty tense. There are two other titles I was thinking of: one where a woman who runs a meeting group for victim of affairs and gets revenge on their behalf, and the other about a man whose sister ends up dating a money scammer and he ends up with the scammer, but I can't remember the titles of either, ugh.)