My bestfriend (M17), Orion, and I (X17) are incredibly close. We've been friends for roughly four years. He is my other half and knows me as well as I know myself, sometimes better. He has said I know him just as well. We constantly express our love for one another and are physically close. Speaking to him comes very easy for me and I feel as though I speak to him more about certain things than I do my own boyfriend. We spend whatever time we have in each others company and call nearly every night. Not only that, but we are comfortable enough in our relationship to give each other small kisses on the top of the head or on the hand. All of this is to say that we are very, very close.
My bestfriend had liked his boyfriend (M17), Matthew, for about a year before they got together and they've been dating for about eight months. I was friends with Matthew before he had developed a crush on him, so we are all friends, with me having known Orion the longest.
This year, we have nearly all our classes together and Orion and I only have one together. While it started off great, I've noticed my growing jealousy of Matthew. It started about three or four weeks ago. Orion and Matthew are, obviously, very close as they are dating. They often speak to each other a lot and are very physically close. That is not to say that they exclude me, because they do not. We speak a lot. Despite this, I still find myself getting jealous and distant. Eventually it evolves into me feeling as if they'd have a better time without me there, even though I know its not true, in Orion's case at least. I feel like Matthew is starting to feel my upset and I don't want that on him because its not his fault at all. What can I do to stop this? I hate this feeling
TL;DR – My best friend and I are very close, but I've found myself jealous of his boyfriend and the closeness that they have. How can I fix this?