>>40
Affection, infatuation, romantic love caries with it the desire to care for someone in ways that friends don't. Sex is a part of this, but believe it or not, you are the first one in this thread to bring it up!.
There is no switch to love on and off, but it fades away with time or cruelty.
There is no magical umbilical cord connecting two people who are in love, their emotional states are independent of each other.
Lust is obviously much easier to deny, and is a separate but not mutually exclusive thing.

Attachment, admiration, friendship, kinship are all separate emotional experiences.
The love you feel for your mother is quite different than the love you feel for your lover.
Unless you're a friend of Freud.

> It grows over time, and needs to be tended and cared for.

Who's to say it isn't?
When a man or woman refuses to move on after rejection, they may interpret the other person's behaviour in the wrong light, or retreat to that old fantasy where they win reciprocation, and the happiness they expect to come with it.
Even if the lovesick fool doesn't even know the object of affection, they can still fall in love with the idea of a person.
History and literature are full of this kind of shit.

> the rational human

Humans are not rational.
I'd like to see you rationally manage yourself when you walk in on your "true love" fucking your best friend.