It would have been considerate for him to answer but it isn't the end of the world. Give him more time and he may have a legitimate reason. If you interrogate him he may reconsider his feelings so exercise some patience. If he hasn't replied by the end of the day then say something like - I realize your busy but my heart is on the line right now so I was hoping for an answer. Don't be critical though. I realize your concerns but don't let them dictate this situation. He did not hurt you. Keep telling yourself that. If you anticipate pain you are going to effect how he sees this relationship. Give him some credit and try to have positive communications without a bunch of limits.
If this has been helpful press accept