I feel like this is best summed up by a great Dr Cox quote from Scrubs:
"Relationships don't work the way they do on television and in the movies. Will they, won't they, and then they finally do and they're happy forever... gimme a break. Nine out of ten of them end because they weren't right for each other to begin with and half the ones who get married get divorced anyway, and I'm telling you right now through all the stuff I have not become a cynic, I haven't. Yes, I do happen to believe love is mainly about pushing chocolate covered candies, and, you know, in some cultures, a chicken. You can call me a sucker, I don't care, because I do believe in it. Bottom line is, couples who are truly right for each other wade through the same crap as everybody else, but the big difference is they don't let it take them down. One of those two people will stand up and fight for that relationship every time if it's right and they're real lucky. One of them will say something."
Their relationship is no more fragile than anybody elses, but what matters is how they deal with that. Will they let it shatter or will they fight for it? And if they fight for it, will it work? Because, at the end of the day, if they want it to work, then it can work, but they've got to be willing to put in the effort and that's what's being tested right now.