I'd put my money on a bit of both, but I'd put more of that money on the causation side. As a thought experiment, imagine going through situations where you ha

I'd put my money on a bit of both, but I'd put more of that money on the causation side. As a thought experiment, imagine going through situations where you had no choice with somebody who becomes the only person you can count on. Not only can you expect to be able to count on that person in the future, but you have an exclusively shared experience. Both of those happen regardless of whether either of you had a choice.