A lot of people think that the vagina is a tube that’s always open. It’s not. It’s a muscle that when there is nothing inside it (i.e. a finger, penis, or tampon), the walls close and touch each other. A woman is not walking around with an open hole in her body.
So when you say she’s too loose, I’m telling you that that’s medically impossible. So what’s going on? Well, it could be one or more possible things.
Things are too slick
When I’m too excited or on my period, things can get too slick and wet. This eliminates any sort of friction that makes sex feel good. My husband says he doesn’t feel anything and I don’t either. Try wiping away excessive wetness and see how that feels. You are used to/want a tighter squeeze
Remember, the vagina’s walls squeeze shut naturally. However some women’s walls may not squeeze shut as tightly as what you are used to. Every vagina is different. Kegel exercises can help with some of that (if she chooses to do them), but every vagina is different.