Grief is part of living but I so rarely have to deal with it, that I'm thoroughly thrown off when it hits me. I don't mean little loss-ey aches or ephemeral sadnesses. I mean real, gut wrenching grief. I can say there are 2 times that Real Grief has staggered me. Once I lost a family member. The other time, a family member threatened to leave me abruptly.
Grief seems to be tied up with bodies, at least for me. It has to do with my body feeling like it will never experience that other body again. I'm not sure about this, still sorting it out.