 Although they both feel jealousy when the other receives significant attention from the opposite sex, Penny is secure enough in their relationship to send him off on an exciting four-month expedition without worrying in "The Bon Voyage Reaction".After Leonard returns, their relationship blossoms over the seventh season.In the penultimate episode "The Gorilla Dissolution", Penny admits that they should marry and when Leonard realizes that she is serious, he proposes with a ring that he had been saving for years.