He may be so attentive when he is with you but rarely communicates when you are not with him because he is seeing other girls.
He may be allocating his time with each individual girl.
Thereby, there is a good chance that you are not the only girl he is giving this kind of treatment to.
When he is with each girl, he gives them his undivided attention but then he has to move on to the next and he only has so much time in the day.
Therefore, he can’t really keep you all happy with his attention all at the same time.
This is one reason.
However, another reason could be that he feels like you don’t really offer him much outside of what you do for him when he is with you.
In other words, he may feel that though you are someone that he is attracted to, you are not really someone that he enjoys talking to when you aren’t face to face.
He may believe that your conversations tend to be boring or monotonous.
Perhaps you talk about the same thing over and over.
When he is physically with you, he would be able to handle this.
However, when he isn’t physically with you, he may feel like he doesn’t want to put himself through the process of having a boring conversation with you.
Another reason why he may be doing this is because he may believe that you are not open to doing things outside of your comfort zone.
He may enjoy engaging in particular activities that he knows that you aren’t a big proponent of.
When he is not with you, he is involved in those activities and as result, he doesn’t think about you.
While he is in his element, he is engaged and you just don’t cross his mind.
You should also consider the possibility that he may look at you as a casual partner or relationship.
There may be a big part of him that doesn’t see you as someone that he will be dating in the long-term.
You may simply be short-term fun for him.
A guy who is considering being exclusively with a girl for a long-term relationship would typically want to talk to her more often.
He sees a future with her and he communicates.
He does this because he wants to maintain that connection and build that rapport.
He also does it because he doesn’t want anyone else to get in-between the both of them. He would not want to risk losing you.
In this case, if you are rarely hearing from him when he is not with you, he may not be genuinely afraid of losing you nor interested in building rapport.
This typically means that he may not see a future with you.
Also, understand that there are some guys who may not be ready for a relationship at this point.
You may rarely hear from him when you are not together because he doesn’t want a serious relationship with anyone.
This means that you have to really figure out what you want and how important that is to you.
If you want a serious relationship and he is not willing to give it, you may want to truly consider if this is the best place to be in for you.