Sounds more to me that you have started to grow up and away from some childhood fantasies that get in the way of real life.
Trying to keep friendships alive when the common ground of high school evaporates...that doesn't exist so good in the real world when your life changes direction as a career and life goals intrude.
You've become responsible and aware of other peoples needs are as important as yours where your "friends" are wrapped up in them yet it sounds.
Seeing that first horse only through child eyes is a rude awakening I think many of us have had occur as an adult...you can not compare child dreams with real life adventures of a adults eyes now seeing things with.
You need to find you and be happy & content with you first before you will find joy in your life.
Riding is a solitary endeavor whether you are with friends or not, true riding is between you and that horse you are astride. Being surrounded by people at a barn... it is a place you do your thing
and converse with them about their thing.
Stop trying to find that now dead horse....stop looking for it, it is gone in reality and what we think we remember.
Every horse is worth a chance to show you why they are special...look for it.
Compare to not another...its hard to not do, but you will never have your first horse ever again, fact.
For you, you are a unique special person.
No matter what it is in life, nothing just falls in your lap that you truly don't work some for...
Somethings you work so hard for an make tiny forward steps, sometimes you have a epiphany and suddenly a large jump in understanding occurs along with your body doing what your mind has been telling it to do.
Do not compare you to another...compare you to you.
You need to find what makes you happy deep inside first.
You have to be your own friend and like/love you...
Be content to be with only you...
Then and only then can you venture outside that small box to find if others can share things with you but not stomp on you and your happiness..
It took me years to figure out what that meant, being happy in your own skin with only you.
My apologies for sounding so harsh...
You have so much to offer...but you need to find happiness inside you first before you find it outside of you, forcing a bravado to the world and miserable inside.
You've already started that journey by writing what you did...your rosy glasses becoming clearer and again will turn rose shaded when you find happiness with you, just you first.