All the romantic comedy conventions are shamelessly on parade in "The Proposal," trampling on our brains and turning them into mush.

They include an uptight character who literally lets her hair down to show she's loosening up, a spontaneous sing-along, wacky relatives, a shocking mid-wedding revelation, a mad dash to the airport and, finally, some very public I-love-yous.

Where is the creativity, people? By definition, this is a predictable genre - a guy and a girl who are clearly meant for each other eventually end up together, despite the many madcap obstacles and misunderstandings that come their way. We know the destination before we even park the car at the multiplex; it's how we get there that matters.

"The Proposal" seemed to be getting there with some spark and ingenuity, led by a couple of actors with solid comic chops. Sandra Bullock and Ryan Reynolds are both well suited for snappy banter and they play off each other with some nice friction off the top. Bullock has always shown a flair for physical humour, but here she gets a chance to play a scheming, tyrannical New York book editor, which is a refreshing change from her frequently daffy winsomeness.

But Anne Fletcher (who also directed the by-the-numbers "27 Dresses") and screenwriter Peter Chiarelli obliterate any good will they'd generated when "The Proposal" turns gushy, piles on the contrivances and goes precipitously downhill in the final act.

Bullock stars as Margaret Tate, a rigid Canadian who's on the verge of being deported. She blackmails her put-upon assistant, aspiring editor Andrew Paxton (played by real Canadian Reynolds) into marrying her to stay in the country. Think they'll fall in love for real? In three days, no less?

That's where Andrew drags Margaret to meet his family to convince a persistent immigration official that they're a real couple. Some typical fish-out-of-water antics ensue. Margaret wears four-inch Christian Louboutin pumps and schleps her matching Louis Vuitton luggage for the weekend. She samples the local cuisine with horror. For her bachelorette party, Andrew's mom (Mary Steenburgen), grandmother (Betty White) and other family friends drag her to a bar for a little entertainment from a male stripper (Oscar Nunez, who has multiple functions on the island, none of which is terribly amusing).

White also gets repeatedly stranded here with awkward gags that don't even come close to making the most of her comic talents. She's more than capable of raunchy humour, which has always provided an endearing contrast with her prim looks; here, she's merely asked to look silly.

But we know these folksy folks will wear down Margaret's defences, and in no time she lets down her uptight ponytail and realizes maybe there's more to Andrew than she'd previously realized. Seeing him naked probably also helped - it sure doesn't hurt - in a scene in which both actors strip down to basically nothing. Both have been to the gym, it seems.

As bickering co-workers, they're a great fit. As potential romantic partners, not so much - and the 12-year age difference is only part of what makes their connection seem implausible. There's also the small problem of Margaret abandoning everything that defined her faster than you can say "I do."