I personally believe God puts people in front of us to love (as friends, as family, etc). We choose how, we make the commitment and do the work. With some relationships it's more work than with others, but just because it's easier doesn't mean its more worthwhile.
I think we're made to be able to heal from our spouse's death or if they leave us, and move on, but I don't think we're built to go through a lot of people/relationships--you know, serially. And we do that so often now -- it takes a big toll on our emotions and psyche.
sg Love is PATIENT, love is KIND, LOVE never fails / DB since 2001
