which would bring us to a possible conclusion that it's not living together that's a problem, but rather - expectations... and there is a lot to be said about the destructive forces of one's expectations. Love is mostly about acceptance, and expectations is the exact opposite of acceptance.
However, this is not to say that we shouldn't first try to find a person with similar value system as ours. However, even with that in mind, I'm noticing that most people are not looking for someone with similar value system as in "I like to eat cookies, so I am looking for someone who also likes to eat cookies", but rather "I like to eat cookies, so I need my loved one to give me his/her cookies". That's how most people define "having similar interests".