It's certainly not a *good* card to get in a relationship outcome position, because oftentimes it represents disappointments that have already happened, or that are present in the relationship now. Usually when people read on relationships, it's understood that the relationship is having some issues (hence why they need to consult the cards for answers). The five of cups in the case of your friend could likely signify the relationship ending, or going through a rough patch, due to the culmination of problems that have been building up for a while. But the good news is that there are two cups still standing, so whatever happens will always have a silver lining.
EDIT: I noticed this card was in the "near future" and not the "outcome." So this makes it a little less of a blow. It could still mean a break up, but depending on what the surrounding cards are, especially the outcome card, it could just mean arguments or other issues.