A thought occurred to me, which strikes me as a different way of stating the importance of shared values:

The best relationships are between two people who respectively value most highly the things which they naturally do well or the qualities that they most reliably emulate.

Not that I'm an expert or anything; relationships are not my strong suit.

But this seems like an efficient relationship. It would entail the least amount of change and compromise. While we shouldn't resist change where it constitutes improvement, the idea of changing simply to become more compatible with someone else strikes me as inefficient, among other things.