Beautiful Lies (2010)
Chosen by me as I like to go to the cinema a lot.
It starts as a moderately amusing, nicely played farce - with anonymous letters declaring love, mix-ups in communication and other silliness but actually has a rather depressing, sometimes creepy undercurrent.
To the film's credit it does not ignore this and barring the very forced ending explores these issues, which might not make for a laugh-a-minute comedy but at least follows through on actually how horrible the main character is being, even if for a good reason.
One moment of the film, which seems played for joyous celebration (following a ladies feet as she walks down the street and starts to skip and dance along) is almost too much as her happiness is based on a deception you know will come crashing down and takes on an unbearable Final Destination-esque quality. Plus this comes after an extended sequence of the woman walking through town with no shoes on (something that creeps me out and I used to have recurring anxiety dreams about) so this section is to me more akin to a horror film than a rom-com.
Which makes it a pretty interesting film really.