Worst ending? (Spoilers)

He WAS in an acapella group, he was just jokingly trying to backtrack on that embarrassing tidbit, which is why she says "nice try" jokingly back. He was also in the boy scouts, all of his nerds stuff was true, and what she genuinely liked him for.

Sure the ending was cliche, but that's kind of the territory when it comes to rom coms...

Also movies cannot jump the shark, that's a television term reserved for television regarding shows that have run too long and run out of story, so writers do something outrageous ( Fonzie literally jumping over a shark) to nab ratings.
This movie's ending was far from outrageous....maybe a little bit lazy, but as I said, tends to go with the territory.

Not only was he a LIAR, he tried to get his roommate to lie to his girlfriend about the pornography, or pictures of actresses...whatever, a lie is a lie and a definite relationship killer.