People change, their learn new things and their wants and objectives change.
I would be wary of considering a failure that somebody who started with the aim of running a coffee shop forever, at some point changed their minds and quit.
It depends on how they quit - if it was good while it lasted and it was their own choice to quit because their hearth wasn’t in it anymore or even for hard-nosed business reasons, it doesn’t sound like a failure to me. For me a failure would be quiting against one’s wishes. In fact I would see the staying running a business you’re fed up with against your wishes a failure.
As for relationships, some of the biggest failures I’ve seen involved people staying in something that had become hellish “for the sake of children”, due to money constraints or just for keeping up with appearences, whilst I would consider a successful relationship when people live well together for some years and when they do drift apart do the adult mature thing and separate by mutual agreement, often still being friends afterwards.