I'm not sure if I'm being unreasonable - please be kind as I'm feeling quite sad about this.
I have 2 friends who are like family to me and who I've known for most of my life, let's call them X and Y. They did a joint speech at my wedding and X and I did a joint speech at Y's wedding, which is a good indication of how our friendships work - we have our individual friendships with each other which can shift and vary in closeness over time, but we are also part of a larger group and in that context, as well as in my own way of thinking, the three of us are known as a trio. There may be times when X and I have been closer or spent more time together than X and Y, which I see as part of the natural flux of friendships, so this brings me to my next point.
Over the past year or two X and Y have become a lot closer to each other. This began as they do certain activities together which I don't do, but this has evolved over time into a friendship I feel has become more and more exclusive and less inclusive of me, so much so that when the three of us went out for dinner several months back, I felt really uncomfortable at the amount of in-jokes and references made and didn't enjoy myself at all.
In the past few months I've moved overseas and both X and Y came to see me off at the airport, but even then it felt as though I was on the outside and they had very much formed a unit of their own. Since then contact from both of them has been sporadic. I've initiated frequently and sent them gifts etc. but I've had lukewarm responses, and whenever I ask one of them what they're up to they're doing things with the other.
AIBU to be sad about this and feel forgotten because they clearly want to be closer friends with each other than they do with me? Is this just part of the natural variation in levels of closeness within friendships which I should just accept and hope that someday we'll be able to pick up our friendships where we left off?