How can someone get "bored" from their pet, but cry a lot when they lose them?

I've had many friends that didn't gave enough attention to their pets, mostly dogs. They wouldn't take them out at all, go for walks etc. But the moment they lose their pet, they would post it on social media, cry about it. The real question is how can you get bored of your pet? Like you are the only person that they are close to.