Do you prefer walks on the beach with one partner, and hikes with another? Do you like piña coladas?
...The point of this line of questioning is not actually to write a personal ad for someone we'd like to escape with, but rather to make us take a moment to reflect on the different relationships we're actually in and the ways the people we're in help us reflect different parts of ourselves, even in similar activities. I find that polyamorous people do a lot of this thinking when trying to institute or enforce a hierarchy, and not much otherwise. Differentiation of relationships in the sense of "you ONLY do this thing with ME and it makes us and our relationship special" becomes more common, and it becomes kind of a dirty word to talk about wanting differentiation or specialness in your relationship even though it's very natural to want that. Without seeing exclusivity as part of it, looking at the feelings associated with particular activities with different people and seeing which ones feel extra good or extra special and how those are differently composed in different relationships can help you identify and have at hand "what is special" about a particular relationship. Having a better answer than "just because you're you" for when partners need reassurance can be really important sometimes.
That example I opened with, the difference of a generally active and outdoorsy person preferring walks on the beach with one person and hikes with another, is one of those "does it matter?" differences... well, no, except that those details are what build the feel of a relationship. Some people struggle more with culturally suggested feelings of relationships not being "special enough" if they aren't monogamous, or if not enough is held exclusive to them - and reflecting on the bits of feeling and combinations of "how we do the thing" that are different from "how I and other partners do the thing" can help sometimes. You don't have to change anything about how you operate or how your partner carries on relationships in order to feel special about yours.