(This could have been a reply to a couple of your comments, but I was reading this one just now, so it goes here.)

Best case scenario, your SO is an admirable person who you're compatible with and who brings happiness to your life. I think that this is fine, but that it strays from the absolute and romantic idea that people seem to have about love. I can't imagine any guy saying to his wife, "I love you. You're great. But you know, there are probably a good handful of people I've met in my life who I could have grown to love the way that I love you if I really got to know them. And there's probably many more people in this world who I could have grown to love the way I love you if I got to know them well enough. In fact, there are probably people in the world that I would be more compatible with than I am with you. You're great, but you're not the only one in this universe that is capable of providing me with what you provide me. That doesn't mean that I want to break up with you. I'm content with what you provide me, and I think that you're pretty good. The point is just that you probably aren't the best, and that you probably aren't the only one. Absolutes are rarely true."

You seem to be both critiquing the "Hollywood" view of romance and love, while at the same time using it as your own view on how love and romance work.

Romance and love can be about total dedication to a single person, but it doesn't have to be. It's perfectly possible to be in a committed romantic relationship while both parties know (and are willing to discuss) that the fact that they're together is a rather random event, which has been influenced by a lot of factors and that if those factors were different, they would have ended up with different people.

So I can perfectly imagine a man saying that to his wife, and his wife accepting the explanation perfectly and it doesn't require two rationalists in a relationship. I'm pretty sure me and my girlfriend have had a conversation of that nature (anecdotal evidence alert).