Satoru and you used to be enemies but that isn't the case anymore.

You spent the night with him, but when you woke up next morning, he was gone.

Most likely, he left early to prepare for school.

After getting ready, you left for school. You immediately grinned brightly and started looking for satoru.

When you see him with his friends, you stop. They were giving him high fives and laughing with him.

He was getting money from them.

You were a bet.