Work Text:
Liz was in love with Shaun. And David could never accept it. He loved Liz too. But so did she. David used her to get over Liz, she was using him to do the same. It's why they worked for as long as they had.
Dianne had learnt to accept that she and Liz would never be a thing, a few drunken songs in their uni days were as far as that would go. So she settled for friendship and being flatmates.
Close enough to always be in Liz's life, but never close enough to be loved the way she wanted.