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 towards a situation or a person keeps you in an emotional holding pattern. Your ambivalent mind draws you in and then pushes you away. Essentially, you live your life in an approach-avoidance style.
As a result, this rigid cycling pattern never moves you forward. You are constantly moving from one side of the fence to the other. "Do I want this? I think maybe I don't. " I really like her, but sometimes I'm not so sure." Or you park yourself entirely on the fence. I'm not making any decisions about thing.
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're involved with someone who is chronically ambivalent, keep an eye on the grains of sand in the hourglass. You may have to detach yourself from an ambivalent person if the connection is an unhealthy.