what is to love someone??

generally I dont talk about love much. But recently I dont know what has happened to me this Love topic is bugging me, I cant read, cant eat, cant think, cant have sex, almost cannot do anything..

When people meet, fell in Love what does that mean? Lust or just want some company to spent boring time, or for just status stuff??

I believe in the institution of love but I dont get it at all.

okay lemme tell you a story about one of my friend who is gay. This guy is a very sweet guy and he fell in love with 1 guy who used to live near his neighborhood. They were in love for almost 2 years.
Later this guy, decided to move to his hometown (somewhere on the earth..lol) and my friend left everything his job, hos career, his home to live with his lover in some other place (somewhere on the earth...lol)
His parents tried all means to stop him, but all in vain. He went there ( somewhere on the earth..lol) lived with him happily for around 9 months.

So after the 2 years and 9 months love affair they parted away. Reason the lover guy got bored of the relationship and started dating other guy.
Now my friend is really in trouble, as they live in same apartment and he sees his ex everyday.
And still my friend hopes for his lover to come back to him.

Isn't this ridiculously insane? Isnt he have self respect of getting off him and move back to his place rather than wait and stay over there like a laid jerk...

I dont understand this ridiculous behavior we all friends tried to convince him but all fell on deaf ears...

What is this? love? or stupidity? I dont get these things...
Im happy to be away from such love sickness which gives nothing but pain...