Definitely my DH and I was closer to him than my sibling within a few months of meeting really. We're definitely "soul mates" and have been for 39 years.
I've never "not got on" with my sister, but we're very different people, different interests and attitudes. We were very close when we were young and did everything with each other or our parents, but as we moved into adulthood, college, and workplace, we drifted apart. No dramas, no big arguments, etc., but we got our own friends, got different hobbies/sports etc. We could go weeks or even months without texting/speaking, not because we didn't want to, but because we had little in common.
Exactly the same with DH and his brother. They were likewise very close as children, but drifted apart once they got jobs, girlfriends, etc. He probably only speaks to his brother once a year, again, no disagreements/arguments, but again, just nothing in common.