Tener celos vs ser celosa

Question

Why does the affirmative phrase use "tener celos" while the negative phrase uses "ser celosa"?

Yo creo que Marta tiene celos.
I think Marta is jealous.

Yo no creo que María sea celosa.

I don't think María is jealous.

Thanks!

Accepted Answer

Hola Chris
There's no special reason, it's only that we expressed the same thing in two different ways (tener celos or ser celoso/-a both mean "to be jealous", although the first one literally means "to have jealousy") - I'll change it so we use the same expression in both the affirmative and the negative phrase so it doesn't create confusion. So now you have:
Yo creo que María tiene celos. (indicative)
Yo no creo que María tenga celos. (subjunctive)
Saludos
Inma