Episode 81 of "7th Heaven"
s04e15 Love Me, Loves Me Not

It's Valentine's Day and the Camden's are celebrating the day of love with a special party in honor of the twins first birthday. Eric and Annie fret over how to make the babies birthday a memorable one, while the rest of the family learn different ways of exchanging love on Cupid's Day. After finally gaining her parent's trust, Mary is allowed to spend a romantic dinner with Robbie, only to learn he has ulterior motives. Meanwhile, Simon and Deena confess to their parent's that they've given each other love bites. Also, Matt welcomes his ex-girlfriend Heather back into his life, threatening his relationship with Shana.