I originally just had the guy's line and left it at that-- it had the requisite amount of bleakness
But then the more I thought about it, the story was incomplete. In the first version, it's just some stupid guy who's probably me, or whatever, and he just says this and stares at the person of interest across from him like he's just dropped some huge, meaningful bomb, but he hasn't; he doesn't know her well enough to see that she's just as jaded and bitter as he is, because he's too busy being a husk of a human being-- who cares? Go be a husk somewhere else.
Now I think it's a time traveling romantic comedy. Hear me out.
These two have met many times, and because they're always at approximately the same life stages and psychological states, they fall for each other every time. Somehow, though, something always comes up to get them into a fight or forces them to move far away or whatever, and what's worse, they forget the details of each time they come into contact, so that it's new (but oddly familiar) each time they meet.
We arrive at the present day: they are in their 40s and have plenty of emotional battle scars from the past, and this time when they find each other it's so grounded and maybe a little cautious that they actually sit down to try to work out why each feels so familiar to the other. This is where some trivial detail from an earlier scene would have to pay off- I'm thinking, in a previous iteration of their relationship, they were at this same restaurant behind a famous person, and are in the background of a picture of that famous person which now hangs on the wall- and they see their young selves clearly together and in love, but at least ten years before they think they even met.
What could it be? Really convincing doppelgängers? No way. This is where their conversation goes something like the cartoon above. If you're still reading, you're probably like, "dude, I was promised time travel elements to this romantic comedy". Hold on a sec, because I didn't intend to write the synopsis of a movie when I typed the first paragraphs of this post. I suddenly got a beginning and an end of the story in mind, and now I have to figure out the late middle and it's hard, OK?
What needs to happen is, they realize/start to remember (whether in this scene or soon after) that they did meet over and over, but got torn apart by some mysterious force. They also realize that at those times, their love would have fizzled out, and the mysterious force sort of did them a favor.
What I don't know how to do is reveal that it was their future selves doing all that manipulating. The time travel element requires some explanation, and I'd rather not make it too goofy. But it's also true that really good science fiction uses its fictional science and technology as a vehicle to put its characters into (and get them out of) interesting situations, not vice versa. In the case of these two, it's what they use once they realize it's the only way to make sure they end up together only when they're ready to stay together.
I guess that places this type of time travel in the category of single, unchanged timeline where the time travel always occurred, Novikov-style.
Anyway, once they figure out how and decide that it's what they have to do since they've already done it, the movie would end with a montage of them going back to every previous instance of their relationships and watching fondly before splitting their past selves apart. Each previous scene is shown from a different angle to show that they were there every time, shaping their lives.
A possible twist: the time travel breaks as soon as they go back to the first point, stranding them in the same time-speed as their young selves. They grow old while living in the past and making sure their young selves keep getting separated until they're ready.
I don't know how coherent any of that was, but I'm going to put it on the internet anyway. These are but the frenzied plot lines of a sleep-deprived mind.