About 2.5 seconds
I give myself about 2.5 seconds because that's the estimated time I have to lift my middle finger up to flip them off. I've liked people before but I don't chase if they don't feel the same. I accept it and move on.
As long as you want
Well the feeling HAS lasted 12 or 13 years, in the past; but it will last longer than that in future I expect.
Not very long.
not at all,i may not tick the required boxes.