the whys of relationships / have reached a plateau, am frustrated! want to see a place to grow!

I've been thinking about the nature of relationships (both platonic and romantic) lately. I define a relationship as a connection between two people, deliberately deepened by sharing time, energy, and thoughts/feelings. And what is the point of relationships? I think that is the part that confuses me because I used to have really clear goals in my relationships. Goals like learning to trust and learning how to be honest and open and learning how to give&require respect. Now I've pretty much got that down and I don't know where to go from there. I don't have an easy WHY for any of my relationships, other than wanting to learn everything about everyone, and that's really unfocused and makes me feel like I'm stagnating.
I'm looking for a new focus. I feel like I don't know how to 'do' relationships, they're too easy -- it feels like nothing is happening. I feel like I'm in between stages. What is the next step? is it having more deep relationships simultaneously? or is there some kind of way to increase friendship beyond what I've experienced? I feel like there must be. I just don't feel like I'm learning anything new (in this way) and I find that frustrating. I know this sounds absolutely insane, and it feels insane, because I am developing new (and old) relationships and they aren't easy of course, but it feels like I already know all the ways to troubleshoot, so even though they certainly take effort, they don't take new kinds of thought. And for me the point of life has always been learning -- not just knowledge learning, but experiential learning.
I feel like I make intimacy such a habit that I don't even know what it is anymore; how do you notice the air you breathe? And most of the people I meet have already let me in as much as they're going to, so there's not an increase in intimacy. What is a relationship that doesn't grow? Some people are open to growing closer, but I feel confused about how to do that, because I've already done the work to let them in. It was so satisfying when it was all new to me and I had relationships where we fumbled along together. Now I feel like the unexplored parts of my heart are very very close to the core, so it just takes a person a long time to get there, whereas most people have unexplored places just inside the gates. And I miss that sense of wonder that comes with discovering a new part of yourself with someone else. I REALLY miss that. Even though I do have it with a few of my relationships, I miss having it with ALL my relationships. I'm a wonder junkie, maybe. I'm a learning junkie for sure, and I feel
But I think I've felt this way before (not about relationships, but I can't remember what it was) so I'm hoping that the shift will hurry up and I'll be back to feeling properly awed by how much I have yet to learn. If I can't level up, I don't wanna play anymore. I'm sure I CAN but I find it really frustrating to have no new path ahead of me, relationally. There's plenty new in other areas but I want to see places I can grow in learning how to have relationships.
Maybe it's something to do with my spirituality, integrating that more into my relationships. I've been feeling directionless there too. On a whim the other day I went to my old church for just a taste of communal love and even the worship had gone utterly stale. Which is to be expected since the leader has gone deeper and deeper into ridiculous dogma, but still shocking because I'd always felt magic in the worship.
My sister and I believe a bit differently. We cling to our favorites to the extent that we will actually purchase said book or movie with the intent of ruminating over it time after time after time. To my parents, this is a waste of money. There are video stores and libraries, so why do we have to own? Why do we have to keep coming back for more and more?
I wish I had an easy answer to this question, because I truly believe that therein lies the key to a lot of my own mentalities. But the truth is that I can't sum up my reasoning in a concise, pretty sentence. Why do I feel the need to own things that I've already experienced once? My desire is always to experience something more than just a single time. I have favorites, because each and every time I experience them, I gain a nuance of information that I didn't have before. Whether it's something as simple as having missed a line of the movie, or something as complex as opening myself up to the reason behind a certain mentality. I enjoy the challenge of picking things apart. I'm the type of person who would tear a clock apart to see what it contains, though I know from the get go I don't have the skills to put it back together again.
What does that say for the questions you've posed here? I don't know. My mom and dad have a philosophy that works for them, because to them the world is always brand spanking and new. And I have a philosophy that works for me, because to me, the world always has another layer to peel back.