Hindu gives science of friendship, love, enmity, hatred etc.

Mind's thoughts are classified into four main categories philanthropic, sensual, disruptive and divine.

Philanthropic tendencies include kindness, compassion, mercy...
Sensual tendencies are about legitimate enjoyment through all five senses.
Disruptive tendencies are about illegitimate enjoyment and about harming others mentally or physically.
Divine tendencies are about spiritual quest.

Friendship depends on theses moods. Like tendencies match and friendship is developed. Unlike tendencies produces opposite effect.
Every mind, guided by Maya, keeps on changing these moods in order to make an attempt to seek happiness. Thus there are ups and downs in friendship of any two individual because no two minds can have like moods all the time.

Love is dependent on the concept of receipt of happiness. You will love that person most who you think will make you happy most. You will hate that person who you think is in your way of happiness and you would be neutral to those who, according to you, have potential neither to make you happy nor to make you unhappy. It is interesting to note that what you think and reality may not match.
The definition of true love is to seek happiness of beloved. Since all our actions are directed to seek happiness for ourselves no can even think of others' happiness unless there exists some underlying self happiness

Hence the conclusion. THIS WORLD IS DEVOID OF LOVE. No one can love anyone else until infinite happiness is attained.