People are probably gonna ship you with other people no matter what and it's gonna suck. For now, try to talk to A or his friends and make it clear you don't like them and want them to stop shipping you guys together. If they continue, ignore it and it will probably go away or get a teacher or another adult involved. I think I kinda get what your going through because I've been shipped with other guys at school, including one of my best friends, and people don't listen when I tell them to stop. Everyone's situation is different and I wish I could give you more advice but that's all I have for now. I wish you the best of luck!