The man is sad because he misses the girl that he loves. The distance between them makes him upset and he longs to be beside the girl.
Distance makes the woman's relationship with the man difficult. She gets upset whenever they cannot be together and how difficult relationships can be.
However, some relationships thrive more in a distance. Whenever two people who miss each other come together, it is always a happy thing because they get what they have been longing for; to be together.
There must be balance in all relationships. There must be love, respect, closeness, and even distance.
Sometimes, when two people are close for too long, they get sick of each other and start to fight and have arguments.