3rd Rock from the Sun (1996) : 5x11

Valentines Day is approaching and Tommy hopes to get a hotel room and lose his virginity to Alissa, however, he is nervous when he discovers that she is sexually experienced and so loses his virginity to Mary's niece Tiffany first. Meanwhile, Dick discovers that Mary is seeing a therapist and, paranoid, he starts seeing her too, in order to find out what Mary has been saying about him. Paranoia fills Sally also, when Don gives her a gift which he teasingly says is from her 'secret admirer', and she mistakenly believes she has a stalker.