My husband's (now X) refusal to get a dog was 1 of the 3 reasons I divorced him. People laugh, but I am serious. I saw it as a test to see how we could handle carring for something other than ourselves. I saw many challenges and learning expirences that we'd have to agree how to deal with, not to mention saving money and compromising.
It was very important to me and he totally dismissed it, which in itself was a sign.