Stupid
It started well enough, but lost me when he started throwing the paper planes. I was with him for the first one, which just went straight downwards, but then they started getting all the way across to the other building and my suspended disbelief crashed to the ground.
At which point I just became irritated with the guy for being a dumb litter-lout intent on papering the ground below with hundreds of bits of litter.
Then I got annoyed at the irresponsibility of someone who throws presumably company confidential documents (invoices? orders?) out of the window instead of doing his job.
When the paper planes 'came alive' it all got a bit predictable and even sillier. I ended up hoping he'd be mashed by one of those trucks as he was crossing the road.
Someone so dumb doesn't deserve to get the girl. Instead of spending hours making paper planes he could have spent ten minutes going down in the lift, across the street, up in the other building's lift, and found the woman. Or any number of other more efficient methods of hooking up with her. But given that he was stupid enough in the first place not to notice when she got on a train without him, he's probably far to dumb to think of anything more constructive than reverting to childhood and making paper planes.
I must try not to let this spoil my day....