i'll never leave you - A promise that's as good as a dog’s word. People say it like

A promise that's as good as a dog’s word. People say it like they mean it, but then they leave you for someone else or something stupid.

'I’ll never leave you,' she said, then left for a new job in another city.

'I’ll never leave you,' he said, then left to chase his dreams.

'I’ll never leave you,' she said, then left to be with her boyfriend.