Actually, that’s pretty much the opposite of rational.
Getting dumped sucks, and right now it’s perfectly understandable for you to feel like you’ll never find someone better. It may even seem like a logical conclusion, but it’s not.
The fault in your logic is that you aren’t going to stay the same person you are today. Yes, the emotional turbulence will pass, but more than that, you’re going to continue growing and changing, so it’s perfectly okay if you never find someone better for the person you are at the moment, because that’s not who you’re always going to be.
Whatever you do, don’t set this guy up in your mind to be “the one that got away.” He isn’t, and that’s not really a thing. That kind of thinking is just a bullshit excuse people use to let themselves stay emotionally paralyzed.
Keep your shit together, and start moving on, because the point isn’t to find someone better. The point is to be someone better, and if you do it for yourself, I promise that one day, you’ll look back on the boyfriend who you thought was perfect at the time, and all he’ll seem like is a quaint exercise in early love.