I suggest you and her find a man with a big penis (not somebody you already know) have him over and the 3 of you have a nights fun. = honestly, she's going to "test ride" a bigger penis weather you like it or not, so just join in a have fun with it. It might be a one time deal, but she might be / become a "size queen" and want more & more, bigger & bigger.
No you shouldn't. Let her have it. She'll really enjoy it. But yes, she's telling you that your's is not big enough.
Let her have what she wants. Better that she does it with your knowledge and blessing. She will do it eventually whether you approve or not. Let her enjoy herself ... it could pay major dividends for you. What's your fantasy? I want my wife to get ****** by a huge **** ... And I want a 3 some! Maybe I'll get both of those one day!
you should be worried
I would suggest to get her a *****, I am sure she is satisfied with you, but i think she wants to experiment, maybe she did not got a chance to do so when she was younger, but i personally would not let her go out and have sex with other man. personally it would ruin my relationship.