What you're describing, feels like you're missing someone, but it's actually a response to a psychological void that was created by their absence. The void is shaped with the silhouette of the one who left, and we think that only this individual can perfectly fill the shape of this emptiness...

But experience says otherwise--even if the individual were to come back--most of the time you will relive and repeat the same things that led to the separation, only this time the void will take another shape... it will take the shape of you.

You are the only one that can close the emptiness that is left by another person. You miss them, but you also miss a part of yourself that was happy. That part may feel like it gone with the the other person, but you can reclaim it as soon as you're ready.