16 a junior in high school and 18 freshman college. pretty sure he liked me his senior years school. but now only emails or talks to if i go 1st. why?

He might be shy. Sometimes people are shy around the people they like. This could be especially true if he's not sure how you feel about him. If he's only comfortable talking to you when you initiate the conversation, it's possible that he's just afraid of putting himself out there.

He might be busy. College is a lot of work, and he may simply not have time to talk to you as much as he'd like. This is especially true if he's taking a heavy course load or if he's involved in extracurricular activities.

He might not be interested in you anymore. It's also possible that he's simply not interested in you anymore. This could be because he's met someone else, or because he's realized that you're not a good match for each other.

If you're not sure why he's only talking to you when you go first, the best thing to do is to ask him. He may be willing to open up to you about what's going on. If he's not, then you'll at least know for sure that you don't have a chance with him.