When you are unable to obtain and keep an erection while watching porn because the pornographic media gets boring, or it doesnt give that umph you need for your member to stand salute.
Fapper's block is the reason there are millions of pornographic genres, and millions more undiscovered...
John: Yo man, teen bukkake doesnt do it for me anymore, im getting fapper's block
When one finally accepts their destiny to be alone forever, and are finally content to spend their evenings alone with the internet, and the endless amount of porn within. Fappily Ever After implies one is happy to spend eternity fapping to porn, hentai, rule 34, pics of nudist beaches, etc.
Greg realized that because of his male pattern baldness, not to mention his halitosis, and being a massive nerd, his only date would be with Rosy Palm. But he was on with that, cause by now he was a master fapper. So, with his phone in one hand and trouser snake in the other, he brought up his favorite porn sites. And he lived Fappily Ever After.