Relationships can be pretty complex at times but I suppose, at the end of the day, they pretty much come down to how we relate.
If a group of friends go off on a holiday together, they're going to return with experiences and vibes they can each relate to, perhaps leaving us feeling like we're not really plugged into their vibe. If friends are more into drugs and drinking, rather than seeking out the natural highs in life, this too will impact our relationship with them/how we relate to them.
We tend to vibe with our tribe, those folk who hold the same sort of energy as us. So, I suppose, we have to ask our self at times 'What's my vibe like at the moment?' I say 'at the moment' because our vibes typically shift on a regular basis, depending on a variety of factors. Myself, I used to be a bit of a drinker in my youth but these days I'm a gal who tends to get drunk on life instead. I never quite click with the drinking tribes when I go out to functions.
In regard to emotional connections: I like to define emotion as 'energy in motion'. If the energy inside me isn't connecting with the energy outside of me, it can definitely leave me feeling disconnected at times.
I did an interesting exercise with my 16yo daughter some weeks back. I asked her to name all the qualities she looks for in a friend. She offered a thoughtful list of wonderful qualities such as someone who can be them self, someone who can be honest, responsible, compassionate, thoughtful, fun and so on. It was quite a long list. I then suggested to her that she look at these traits and ask whether they are the traits she longs to have within herself. She read the list and smiled. Yes, she wishes to be her most authentic self , to be honest, responsible an so on. In many cases, the people we most identify with are those who reflect our own authentic most desired nature.
If you can't relate to the drug scene and moodiness, it's most likely because this is not you. If you can't relate to feeling excluded, I imagine it's because you're someone who likes to thoughtfully include people in conversations or experiences. And if you can't relate to surface level type friendships, perhaps that's because you're a soulful person to some degree. Maybe, you're in the challenging process of finding your self, your true self. Self questioning is often a part of the process in coming to understand who we truly are.
Take care :)