Love is a heartfelt thought of affection, you give conscious or unconscious to something you like -from your self like Narcissus [a Greek legend who fell in love with his own reflection and was turned unto a flower], to your mother, father, family, friends, lover, [even if your relationship with them is bad], animals, social life, career, work, liquor, pigs, money to material possessions, sadism, gossiping, music, TV, high achievers, movies, celebrities etc and this result into emotional attachment to your object of adoration and since every thought carries an emotional tag, you will feel it. And thinking too much about that object of affection in the name of love, budges you to give it to them or express it and if you don't stop thinking about them too hard, it can lead to obsession or infatuation and there is danger there because when we live in expectations with strong belief how things are and how others should be, we will get disappointed because nobody is perfect to live up to anybody's expectation.