How do I feel less lonely in my workplace when I feel like an outcast?

I recently got promoted into a new role with more seniority and responsibilities. I am quite isolated as I am the only one on my team, with the exception of my manager and my previous coworkers who are out on field 80% of the time. Since gaining this position I feel like my coworkers treat me a lot differently, it's not the same rapport we use to have. The other people in my office from other departments have each other, and majority of the time I feel like most conversations with them are superficial as I am meant to be keeping good working relationships with them. These relationships are meant to benefit my department where I can get new clients, which I do but they are very surface level.

I always feel so lonely and miserable at my new role; I love my new job, but the role itself is isolating, and relationships feel superficial. It's just getting new relationships to benefit both parties and nothing more outside of it.

I generally talk to my boyfriend on phone calls during my break time, so I feel less lonely, he knows what I am going through.

Overtime I am starting to just resent people in my office, the superficial niceness and nothing genuine. There is 1 or 2 people that treat me well and ask about my weekends but I feel extremely miserable. I used to work with clients all the time and I was never lonely but now I work with other departments rather than 90% interactions with clients.

I listen to music to make myself happy.

How do I feel less lonely in my workplace when I feel like an outcast?
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