I work as an software engineering intern in my free time and summers at a small startup. Management has consistently asked me to continue, giving me several raises.
However, for some time my direct manager has been acting coldly towards me. For example, when I left last summer, he ignored my email thanking him and asking him for feedback. He jokes and acts friendly towards other employees but is stone-faced when speaking with me.
It is not inconceivable that I said something that offended him; my company often has passionate discussion during breaks where people vociferously defend their opinions. However, I would have expected him to say something to me if that was the case.
Management is asking me about continuing and I am confused. On one hand, I am generally very happy working at this company, and have good relationships with my coworkers. On the other hand, I don't want to work for someone who is angry at me. I would like to ask my manager point-blank what's wrong, but I'm afraid that he may deny it or get very angry at me. I can easily find other work, but I don't want to burn bridges, and would like to stay with the company if possible.
What would be the best way to talk to my manager?