It would be helpful if you were honest with him and told him how you really feel. It's true what another comment said, if he has time to like and comment on another girls pictures, he would have time to message you. Many guys just don't think how this kind of behaviour looks, whether in all innocence or not.
Whatever you have going right now doesn't sound healthy at all, just explain and if he sounds like he's not really invested/has his eye on someone else, just end it. There will be someone else who will care more for you.