You seem to be operating under the assumption that "love" is something that doesn't help people get happy. If you're trying to optimize for personal happiness and love (in whatever form) enhances your ability to be happy and/or directly causes you happiness, love is a perfectly rational thing to do.

You say:

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.

But that doesn't have to happen. You can keep thinking rationally about love, even when under its effects. It's not because we are wired to love by evolution that the love for my family, partner, friends... stops being valuable and gives me happiness.

And I don't know why I'm typing all this, because you seem to have a very narrow definition of love, namely the very specific timeframe in the early part of a romantic relationship. Love is a lot broader than that.

The obsessive part you describe is love, but so is:

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.

And if I had to answer your opening question:

Yes, love tends to be a good idea, but you have to be specific about what type of love and to which degree.

ETA: After re-reading Feeling Rational, I think that the statement "Love is not something that can be destroyed by truth." works better than everything I wrote above and more or less sums up what I'm trying to get across.