Bienvenue, is short for "nous vous souhaitons la bienvenue" So it's with a "e" when you just say "bienvenue" But if you say tu es le bienvenu you have to remove the feminal e Tu es la bienvenue take the "e".

Yeh, she is right. It's always with a "e" because it's féminin. The use of that word is interesting. In French it means "welcome" as you know. In Canadian French (Montréal) it can mean "no prob." Bienvenue can be the same this as De Rien.

it's always "bienvenue" with an e.