5. Penny & Leonard's Engagement
In the last episode of season six, "
The Tangible Affection Proof", Leonard takes Penny out for a Valentine's Day meal accompanied by Howard and Bernadette, and spot one of Penny's ex-boyfriends with his new beau, before he gets down on one knee and pops the question. This stirs up mixed feelings for Penny who realises that her relationship with Leonard is beginning to get serious, and she later confesses as much toward the end of the episode. Leonard then allays her fears and tells her that he won't ever propose to her, and puts the ball in Penny's court r.e nuptials. It seems quite likely then that perhaps at the end of series 6, Penny will get down on one knee and ask Leonard for his hand in marriage, think Monica and Chandler in Friends. We'd love to see this happen and we believe it will really help, if you pardon the pun, "evolve" the series by taking key relationships to an exciting new level.