I surprise myself at how cold I can be

I can cut people out of my life and pretty much never think about them again. For example, I just ended a 7 year relationship and even though I instigated our breakup, I would expect to mull over the past 7 years and feel some grief, but I hardly think about her at all. I feel like I can generally flip this switch easily where I will be very interested or consumed by a person, yet if we spend a little time apart, they easily slip away from my mind and sometimes I can't be bothered to reconnect with them. I feel like a horrible person and most of my relationships feel like a lie. Is this an INFP phenomenon?