It is a very complicated problem to love each other but it is difficult to stay together. In my opinion, there are several possible reasons.
First of all, it is easy to fall in love and difficult to stay together, probably because two people will encounter various challenges and difficulties in the process of getting along. Sometimes, these difficulties may come from personality differences, living habits, family backgrounds, etc. These differences can be uncomfortable for two people and even create contradictions and conflicts. If not communicated and resolved in a timely manner, these conflicts may gradually accumulate and eventually lead to a breakup.
Secondly, it may also be because both parties do not understand and trust each other enough. Sometimes, we can hurt each other because of our own prejudices and misunderstandings, causing us to become more and more distant from each other. Trust is an important factor in maintaining a relationship, and if there is a lack of trust, it is difficult for the relationship to last.
In the end, it may be because the two parties do not have the same plans and expectations for the future. Sometimes, we may have disagreements because we have different ideas and pursuits for the future, and these disagreements can leave us feeling lost and uneasy, not knowing how to choose. If both parties are not able to communicate and negotiate openly, then these issues can become the trigger for a relationship breakdown.
It's easy to fall in love, but that doesn't mean we shouldn't try and try. As long as we are willing to manage and maintain our feelings with our hearts, and tolerate and understand each other with love, then I believe that we will be able to overcome all difficulties and move towards the other side of happiness.