Clark could sing this one to Lois 'True to your Heart' by 98 Degrees feat. Stevie Wonder

Edit: This one is perfect for Clark also Never Gonna Give You Up by Rick Astley (though I probably was all of 3 or 4 when the song was released) this song is a representation of both of them but especially the way Clark feels about Lois except maybe the part never telling a lie to hurt her.

The best and most beautiful things in the world cannot be seen or even touched they must be felt with the heart

Helen Keller