man can fall in love for several reasons

1) Because of Infatuation

2) Loneliness

3) Need for Frenship

4) Hormones always bothering him - for lust,weaknesses - beauty/charm/cheerful smile, voice,nice body etc..

6) because of ego, prestige, high expectations in life 

7) For a relationship  - to want to have family  (NORMAL LOVE)

8) because parents got him married - arranged marriage

9) live with a dog for 6 months, and u fall in love with it too

10) To share weakneeses/strengths, moral support, pain and pleasure to be able to trust, honor, respect, depend on someone ...THE NORMAL LOVE OF A HUMAN BEING. ..TO be a normal human being.