I've searched around on LW for this question, and haven't seen it brought up. Which surprises me, because I think it's an important question.
I'm honestly not sure what I think. One one hand, love clearly leads to an element of happiness when done properly. This seems to be inescapable, probably because it's encoded in our DNA or something. But on the other hand, there's two things that really make me question whether or not love is a good idea.
1) I have a very reductionist viewpoint, on everything. So I always ask myself, "What am I really trying to optimize here, and what is the best way to optimize it?". When I think about it, I come to the conclusion that I'm always trying to optimize my happiness. The answer to the question of, "why does this matter?" is always, "because it makes me happy". So then, the idea of love bothers me, because you sort of throw rational thinking out the window, stop asking why something actually matters, and just decide that this significant other intrinsically matters to you. I question whether this type of thinking is optimal, and personally, whether or not I'm even capable of it.
2) It seems so obsessive, and I question whether or not it makes sense to obsess so much over one thing. This article actually explores the brain chemicals involved in love, and suggests that the chemicals are similar to those that appear in OCD.
Finally, there's the issue of permanence. Not all love is intended to be permanent, but a lot of the time it is. How can you commit to something so permanently? This makes me think of the mind projection fallacy. Perhaps people commit it with love. They think that the object of their desire is intrinsically desirable, when in fact it is the properties of this object that make it desirable. These properties are far from permanent (I'd go as far as to say that they're volatile, at least if you take the long view). So how does it make sense to commit to something so permanently?
So my take is that there is probably a form of love that is rational to take. Something along the lines of enjoying each others company, and caring for one another and stuff, but not being blindly committed to one another, and being honest about the fact that you wouldn't do anything for one another, and will in fact probably grow apart at some point.
What do you guys think?
While others have remarked that you're responding to a "Hollywood" conception of romance, I also want to point out that you aren't the only person who perceives romance this way. The surface perfection of romance is something people would like to signal about their relationships. Like, even in the cases where people are cheating on one another, or the relationship is falling apart, or mired by abuse, or conflict, they like to publicly signal that things are still going well, or at least not going horribly. If you searched for 'romance', or 'relationships', on Overcoming Bias, you could find some decent material on signaling within sexual relationships. Additionally, media besides Hollywood movies are shoving an archetype of romantic relationships down our throats all the time. So, only mostly perceiving all this, there are a great many people who view relationships in this manner. This is probably skewed towards younger people, although it's also been remarked in this thread that some people go through this for decades.
Mr. Zaman's comment seems to point out that a key to finding a relationship that avoids all these things about love which would frustrate you is that you can find the right person to do so. I don't know how to do that myself, per se, other than suggesting you try OKCupid, or altering your social circle to include more people who have a similar mindset, and then dating from within there.
I believe you're correct in that a substantial portion of relationships, one partner coming out to another, and stating (realistically) that they're not the best possible person, and that it could be quite possible to find another one, would be hurtful. I believe that might be hurtful in some relationships only because the other interlocutor won't understand why you're stating obvious but hurtful facts, like you're signaling something mysterious. I wouldn't worry about that, though. So, there are people who have fooled themselves into thinking relationships ought to be like an idealized romance. Perhaps you could try observing other relationship styles where you can, or read about them on some blog which is, I don't know, contra-romantic, and that could change your perception of people practically love one another.