"Ese mensaje fue muy dulce"
So sweet. = Tan dulce.
eres dulce
ricura
There are many sweet messages that you can say to a crush on his birthday. One thing you can say is " I hope you have a magical day."
muy dulce
Ella es dulce.
frijoles dulces.
dulces sueños
There is not exact Spanish equivalent of this. You could say"Mi amorcito" or "Mi corazoncito"
te quiero (Spanish) -> I love you (English)
hola muchacha dulce
mujer/esposa dulce