It was love at first sight for two outgoing romantics. Years later, a chance encounter while on family vacations forces the unrequited soul mates to face the same decision: Continue their comfortable but unfulfilling lives or risk everything for a chance at complete happiness?

Thanks for the links to "Before" trilogy descriptions. I think (like dpg also mentioned) that there are parallels. At least (just judging by the descriptions) the first two.

I haven't seen these movies (clearly I need to, in fact the second film was on my "watch next" list) but I think one of the key differences is that the meet-up that I'm envisioning is random (neither party expected to run into the other) where as in Before it sounds like Celine goes to Jesse's reading, which I think changes the motivation of Celine at least.

One of the things I think I need to make more clear in the logline is that my intent is to have a more humorous tone than Before series (or at least the tone I get from the description of Before) more like a traditional romantic comedy.

The protagonists are the two unrequited, outgoing romantics.
The goal is happiness/fulfillment, but that requires breaking away from their existing (comfortable, but unfulfilling) lives (ending their marriages, hurting their families, etc... <- I guess those would be the stakes as well)

This logline is too vague at the moment. I don't really understand what I'm likely to see in this film. Who is doing what?

As Phil points out above, you can look at Linklater's "Before" trilogy; but in addition to that being about two lovers who never quite get it together, it includes the hook of all taking place in a single night, and is a largely improved series of conversations. Who is your protagonist, what is their goal ... and what are the stakes that will keep me glued to my seat until the credits roll?