I wonder: Is it harder to like or to dislike something or someone over a period of time?
I think maybe it's about the same because, no matter what the protestations of delight or disgust, liking and disliking mean creating a fixed set of descriptions of what is liked or disliked.
Fixed. Things are always changing and yet something or someone we have decided to like or dislike very much always depends on a fixed, stand-still reasoning or emotion.
For this reason, there is a sense of fatigue mixed with a vague hypocrisy that creeps in as we try to extend or lengthen our likes and dislikes, our 'good's' and 'bad's.' And sometimes, when we sense we are losing our grip on a particular person or thing -- something towards which we might like to extend an on-going principle of favor or disfavor -- the tendency to talk louder and use more hyperbole goes up. If you talk louder, maybe you will continue to believe it with the same fervor you once did ... only of course it doesn't work.
Things change. It's easy to say, but harder to do -- harder to get with the program. Enemies of the past are not necessarily enemies of the present. Friends of the past somehow shape-shift into something that seems inimical.
The only thing harder than the fact that things change is insisting that they don't/can't/won't.