I think I can draw some inspiration from "Be Mine", it's actually pretty relatable to me and I think I can make it not so depressing without it being too upbeat and superficial either. My other options were "Almost Doesn't Count" which I felt like I could write a bop to, but I went against that idea because it wouldn't be experience and I think it'd end up something between Flowers and Forever In A Moment.

The second option I considered was "Cracks In Mr. Perfect" which I can also relate to a lot, but I don't want to do something too depressing or cheesy light-at-the-end-of-the-tunnel either.
tl;dr I'm going with "Be Mine".