A lot of people think they know what they want in a partner, but if they are actually lucky enough to get it, they realize that they actually wanted another thing in entirely. Others pretend to be somebody they're not just to get a relationship, and eventually face the consequences; crushes appear to take over a life out of nowhere, and then dissipate as soon as they reach reality.
Yes, part of the reason that romantic love is prized by so many is that so much of the time it is actually fleeting. Getting the ick over things that may seem dumb from the outside can often be a blessing in disguise, because sometimes those stupid things are actually a warning sign of bigger problems or compatibility issues. Other times, it really is just shallow, but perhaps that is for the best anyway.
Even when a relationship doesn't work out, one of the good things about dating is that it can give us a story to tell. The highs and lows of trying to find love always make for a compelling (and occasionally horrifying) tale. Everybody is a little weird, but some people are a lot weirder than others. The unfortunate thing for most who are hoping to be in a relationship is that they have to find this out the hard way. While the stories can be great, that often means that the experience isn't. It is no wonder that some opt out of looking for love altogether.