Because we now have more choice from a greater pool of potential partners, we often unconsciously look for reasons to be displeased with our current partners. Today dissatisfaction with a relationship can be one argument or unmet desire away. We tend to keep score in our relationships and if we feel things aren't tallying up according to some pseudo-analysis or "sign", we end things. Many have the attitude that there are plenty of fish in the sea so to speak, so if their current partner doesn't tick all the boxes needed, you find these people opting to walk out rather than make a decent attempt at rectifying things. Consider that sometimes your partner doesn't know that something they do or don't do is making you unhappy. Have you at least made them aware of this before plotting your exit strategy?
Our grandparents on the other hand stayed together for life. For the most part, did they not seem happy? Sure, you can't stay in a relationship or marriage if there is deep seated incompatibility or differences that cannot be reconciled. But that doesn't mean a relationship must be dropped at the first, second or even third sign of difficulty. Human relationships are not commodities or careers; they are much deeper than that. They are worth persisting with for a bit longer.