Of all the things I've seen in my work, I'd have to say that Ambivalence - the state in which one feels contradictory emotions for a person or a situation - is a rough road. The coexistence of both positive and negative feelings you have toward a person, like love and hate, will draw you in and then push you away. Similarly, the simultaneous approach-avoidance you have with making a decision keeps you in the same holding pattern.
As a result, this rigid cycling pattern never moves you forward. You are constantly moving from one side of the fence to the other. Or you park yourself entirely on the fence.
Ambivalent thinking has been linked to genetic origins akin to obsessive compulsive tendencies, to psychological defensive styles like "splitting" or personality disorders, and underdeveloped cognitive-behavioral styles of problem solving. So if you are ambivalent, there are things you can do to break the holding pattern. Professional help can get you going in the right direction.
If you are involved with someone who is chronically ambivalent, suggest therapy to him or her... and keep an eye on the grains of sand in the hourglass. Sometimes you may have to unhinge from an ambivalent person if the connection is an unhealthy one for you.
PS: Thanks to all for the "E" award.
I nominate all my those on my blogroll as they are totally excellent bloggers!