It's been pointed out that Mike is somewhat of a keystone of the plot.
He has that scene with Marge when he sounds so sincere about being in love with her. Later, she finds out he was lying, and she immediately goes back to talk to Jerry, who had sounded so sincere when she had questioned him before.
"If a person saying he was something was all there was to it, this country'd be full of rich men and good-looking women. Too bad it isn't that easy.... In short, when someone else says you're a writer, that's when you're a writer... not before."
Purveyor of fine science fiction since 1982.