He is hot and then cold...?

It sounds like he's confused about his ual orientation or is having a hard time accepting that he likes guys. If you're in high school, as it sounds like you are, then this is a common issue among teenagers with their first couple big crushes/romantic interests. A lot of the time, people struggling with it will try to control their thoughts/feelings by just trying to stay away from the person they feel is responsible for it, but they have a hard time doing it for good because they really like the person.