Instead of asking "Are you the one," ask two questions of each of you. Do I accept my partner despite their shortcomings? Do I commit to nurture them to achieve what is important to them? And likewise, do they accept me and do they commit to me? All you need is four yeses.
In other words, siblings are forced together, and then suddenly they’re not. The independence of adulthood—when proximity is no longer required and the obligations lessen—creates opportunities for siblings to build, repair, or discard the relationships of their youth, to stay stuck in or break free of the roles they played as children.