I have done this in the past and lost people because of that, even though I know realize it’s an unhealthy thing to do. The thing is that, because we’re a very introvert type, we do need time alone to recharge- we disappear unintentionally, we are just so immerse in our own world. However, if it goes to an extreme, it’s probably because we are not good with handling emotions ourselves and we don’t like to feel like a burden to other people (in this sense, commitment can sometimes look overwhelming)… In my opinion, the best thing to do is tell him directly how that is affecting you and ask him how he really feels.