Check iOS version on your girlfriend's iphone, is it iOS 15.7 or iOS 16? Whatever it is, something of the combo with iPhone 14 and iOS 16 do not work with your hearing aids. As I mentioned earlier, contact your hearing aid providers, and tell them the situation. Also, ask to contact GNResound support line (again, assuming your hearing aid is from GN, you can confirm with your Audiologist if you don't know). Contact GN support line, give them the details.
If someone else you know has a different iPhone 14 model, I think you should try it out. Or, as suggested, go to an Apple store, try all different iOS 14 model to rule out if your phone happens to behave badly.
Whatever it is, yes, I'm pretty sure it is a software update, most likely on Apple iOS. There is a chance on your hearing aids, but you need to find out from your provider.
Oh, my last question posted earlier, on your Android phone, does it suppor hands-free call? See details in my earlier post.