A much healthier than usual version of the whole "We were kind of in love, but one of us is getting married now" shtick—presented as, well, just normal stuff that happens in life. Stuff that didn't work out for benign reasons, with some tacit acknowledgement on the part of the characters along the lines of, "well, that's a shame, but it's not the end of life and it's time to move on".
Which is to say, again, bittersweet, but not rage-inducing or depressing like most incarnations of such a premise is.