I've often suffered (if thats even the right word) this problem. It's not that I don't care about or love the person in question, its that my personality doesn't lend itself to pining over people who aren't there. I love my parents beyond measure and I live in the same city as them. Do I talk to them on the phone everyday, or see them once a week? No. Some might think this makes me a bad person but to be honest, the thought doesn't even pop in my head that "Oh I haven't told my parents about the mundane goings on of my life, I better call them." This happens not only with my parents, but with close friends that live far away. Yes I stay in touch, but its not like I'm taking an hour out of every day (or even every week, or month) to catch up with people.
For me to get in touch with someone, be it friend, GF, family, or w/e, there has to be some material purpose to get in contact. This purpose could be "I'm going up to visit my buddy in DC. I better call him and tell him when I'm flying in and to which airport". I'll never txt or call someone just to say hi. I may say I am, but what is usually happening in that situation is that I'm interested in a girl and wanted to ask her out, or take some other step towards creating a relationship, and used getting in touch as an excuse to further that purpose.
This thread I think highlights a misunderstanding between Ts and Fs that may create a lot of hardship. It seems that many people draw a proportional relationship between attachment and love (or the amount you care). For Ts generally, this is simply not the case.
We might not express our love like other types, but when we love someone, they know it through and through.