Why?

Can't deny the fact that we sometimes encounter things that can instantly turn love to loathe.

It even happens in this way:
http://thestar.com.my/columnists/story.asp?file=/2007/7/29/columnists/senseofstyle/18391668&sec=Sense%20Of%20Style

Nice feelings sometimes wore off abruptly and we make a complete 180 turn.