Well, it is hard to admit to yourself that you aren't capable of taking care of a pet.
Especially dogs because they are resilient and will usually stay by an owner's side until they die.
I can understand not wanting to lose that loyalty.

But my family had a golden retriever a while back. He iw one of those rare dogs that is so smart it can understand commands its never heard before.
My family was doing fine with feeding him and making sure he gets excersize, but they knew he'd be more happy with a family that didn't travel so much. He was in a kennel just about once a month because they'd be out of town.
Eventually, they found a couple who seemed like a good fit for him, you know, active, didn't have to leave him behind so much.
I've seen pictures and the dog is clearly more happy now.

I won't lie, I wanted to take care of the dog, but I realized I'm hardly ever home for more than it takes to shower and sleep.
I may be selfish, but I wouldn't make a dog suffer so I could have another friend to ignore.