Make your lady happy!
Now free him from his chains and lie down on the bed in front of him.
Tell him to take his chance or you will fuck someone else.
Wait until he's inside you, then start explaining to him that you will find a man with a big cock if he doesn't satisfy you right away.
Tell him: I will register on a dating site and you will help me to choose a lover for me. A lover with a much bigger and better cock than yours.
A dating site is a good way to tease him, if you do it right in front of him. Describe exactly what you are looking for: A lover that is well endowed. A lover who can satisfy a neglected woman. Possibly as a threesome with your husband.
After this game you should give this a chance. Maybe you receive some nice pics of big cocks, which you can show to him. Talk dirty with other man, and show the chat to him.
But be careful, don't do it secretly. The effect is better anyway if he can read along.