eres tan dulce
So sweet. = Tan dulce.
Estoy celoso(a); es tan dulce.
eres dulce
ricura
Lo siento mi corazon people dont say sweet heart here. So just say my heart
You can say "Primer grado es dulce" in Spanish. This phrase captures the idea that first grade is sweet or enjoyable.
muy dulce
Ella es dulce.
dulces sueños
frijoles dulces.
There is not exact Spanish equivalent of this. You could say"Mi amorcito" or "Mi corazoncito"
te quiero (Spanish) -> I love you (English)