Have You Ever Really Loved A Woman?
From The Big Bang Theory Wiki
This song by Bryan Adams was playing in Leonard's bedroom when he and Leslie were "getting busy". They'd left a tie on the door handle to signal that they didn't want to be disturbed, prompting Sheldon to go across the hall and get Penny to explain what was going on.
The song was written for the soundtrack of the film "Don Juan DeMarco" and appeared on that soundtrack album and on Adams' "18 Til I Die" album.
