I lost all of my friends

If you fit in, you are accepted by the other people in a group because you are similar to them, share their interests, or behave in the same way.

“narrative that having no friends is an indicator that you need to improve yourself it's an indicator that you don't fit in it's an indicator that you have low social skills or social anxiety She moved to a new school and worried that she wouldn't fit in with the other students. He always felt like he didn't fit in at the corporate office because of his casual style. They are a very welcoming team, so I am sure you will fit in perfectly.”

A tight group is a small collection of people who have a very close relationship, trust each other completely, and spend a lot of time together.

“or try to insult me behind my back they would be there to shut it down immediately as I would for them you know we were a very loyal very tight group of brothers anyways once we hit about the The students in the drama club formed a very tight group by the end of the school year. It can be hard for a new employee to join such a tight group of colleagues. They are a tight-knit group who always support one another through difficult times.”

Acquaintances are people that you know and have met, but who are not close enough to be considered your real friends.

“that trip my friend in California got hit by a train I was trying to word this correctly and when I say got hit by a train you know if if I have many casual acquaintances at work, but only two or three close friends. He bumped into an old acquaintance from university while walking through the city center. They were just acquaintances before the trip, but they returned as best friends.”

(informal) If you say that people have each other's backs, you mean that they are ready to protect, defend, or support one another in difficult situations.

“was four of us but we were really good friends we were like brothers we had each other's backs you know if anybody tried to put a finger on my girlfriend In a successful marriage, both partners must have each other's backs when times get tough. My team at work is amazing; I know they always have my back if I make a mistake. Growing up, my sister and I fought a lot, but we always had each other's backs against bullies.”