The Two Lines on my Plan can’t text each other

I have two lines on my plan, my girlfriend and I. But on her phone, she cant send texts to me specifically. It always goes straight to my email and I'm the only one it does it to. We both have iPhones on the latest update, and we don't share an Apple account. We even went as far as deleting my email off her phone and out of my contact, blocked it, and it still goes to my email. ¿Tienes alguna idea?