Best friend problems

I am in my first year of senior high, New people, school, classes, everything. Me and my (best) friend decided to apply to the same school, but we are now in different classes and don't interact irl much anymore - other than seeing each other in the hallways, but that's pretty much it.

We have known each other 4 years prior as we used to be classmates, they immediately found a friend group on the first day. I, however, did not grow fond of my class, leading to having no valuable connection with any person I have to see every day.

My friend is well aware of my situation as I've told them about it many times, but they don't really seem to care that I'm suffering from the loneliness. They pretend everything is normal and we only have conversations and interact via text. They don't talk to me at school unless I initiate first or when they're with their friends. The only time they want to hang out or talk is when their friends are not around. I'm afraid that the person I consider my BEST friend is ashamed of me?? When I asked if they could introduce me to their new friends, they immediately expressed discomfort and such.

Is this a red flag? Should I confront them?