Why do men lead women on?

Okay I know it's a two why street and some girls do this to. I for one have never done this. I think it's really mean and can be very hurtful especially if the other party is interested because they thought it was mutual. Guys if your not interested in a girl or are in a serious relation maybe engaged or married. Why would you lead a girl on? Why would you act like your interested in her. And for a long period of time not someone you just met, and casually flirted with for a few days I'm talking Months or even years. What do you get out of it? Answer my poll and please elaborate. Thanking you in advance.
Ego boost
Your not happy with your partner
It's fun and you don't care how it comes across as long as your happy
Select gender and age to cast your vote:
Why do men lead women on?
9 Opinion