Generally, no, as it?s quite an easy and lazy plot device to abuse. I mean, it can be nice as an initial exploration or commentary on relationships, but they always tend to be dragged out and get really tiresome towards the end. Notable example is Ross & Rachel in Friends. They had a fucking kid together, for goodness sake, yet they still couldn?t get over that ?We were on a break!? bullshit, and how they were ?terrible? for each other, even though their relationship was years ago, their circumstances (work, etc.) had changed since then, and they practically were going out (providing each other with shoulders to cry on, the occasional bumping of uglies) because they still loved each other and ended up sabotaging every relationship since then (although a lot of them were just episodic, gag-like ones, that are mentioned once and never again).
But, hey, they?re not exactly intolerable as far as sitcom tropes go, and I still love sitcoms such as Friends and Scrubs.