becoming hard hearted- for the best?

After my first relationship ended in 1996 - and it was ever so brief- i became sorta of a hard hearted person when it came to feelings. Then in 2006 my mom had a stroke and i started to change slowly. I started to care about people again. Lately though ive been finding i dont get a lot of those loving (friendhip only) feelings returned, even by those i thought were close. So im thinking its time to go back to neing a hard ass. Any thoughts?