How I Met Your Mother Season 5 Episode 21 (How I Met Your Mother s05e21) with title “Twin Beds” airs on Monday, May 3rd 2010. In this 21st episode, When Ted and Barney jeopardize Robin’s new relationship by professing their love for her, Robin realizes that she is finally over them. Elsewhere, after spending a weekend sleeping in twin beds, Marshall and Lily decide to get twin beds at home.