Here are some possibilities:

1-4-3 means "I Love You"

Three soft taps on the shoulder mean "I Love You"

SWAK = Sealed With A Kiss

X's stand for kisses; O's stand for hugs
(often used to sign letters)

Learn the sign language gesture for "I Love you"

Three soft taps on the thigh mean "Let's make love"

Red roses symbolize love and passion

Pink roses symbolize friendship

Yellow roses symbolize respect

White roses symbolize purity