"He was my North, my South, my East and West,
My working week and my Sunday rest,
My noon, my midnight, my talk, my song;
I thought that love would last forever: I was wrong."
Everybody wants to love and be loved. How do you make it last when it happens?
The cliche - hard work.
The cliche happens to be true. But what does it mean?
Hard work means being able to step outside yourself and experience what the other person is feeling. To listen actively to what the other person is saying. To commit to making the other person's happiness your first priority. To forego you own temporary comfort for the other person's sake. To think often about the other person, what his/her needs and dreams are and how you can help them be fulfilled. To understand what makes the other person feel loved - often different than your own needs.
If you are a guy I would compare it to a complicated sugya that you have to attack from many different angles and untangle the many complexities. Everytime you come back to the sugya, you reveal new depth. A person, a Tzelem Elokim, is no less complex.