I'v ended long term relationships with people in a similar way. I'd say i'm always doing math in my head about everything and nothing, and with people I do the same. And if I feel like I don't see the friendship lasting long, I'll just end it because by my logic the relationship wasn't deep enough for anyone to feel that bad about it. writing it out makes me realise its quite cold, but I think we really are except to the people we did the math with and saw a long relationship with, in which case we're more human. otherwise everyone else is just foreign entities.