You even notice how people seen to like being maudlin, lamenting lost loves, lost opportunities and the like? Why worry about the past? I don't mean to be insensitive, but it seems to me that being sad because someone you cared about is gone is wasted energy better used to living life. It's quite a cliche' but it would seem to me that if that person really cared about you, they wouldn't want to see you wasting your life grieving over them. I would think that they would like to see you live life even fuller than they did. But then, I guess that would be just me.
Some people like to be so low they would need a stair lift to get them up and living again. Again, I'm being insensitive, but I hate hearing "my life is over, he/she is gone". Well, it's over if you let it, I say.