Let me just start out by saying this is not an easy match, but it can be done. It's always two against one, and Scorpio likes to have more of the players on his side, so you can see how this can get tricky. This will take effort and respect from all parties. Gemini is scared by anything that may lock her free soul down, and Scorpio likes things to be promised. In Scorpio's world promises are always meant to be kept, but with Gemini the change of the wind can bring out the other twin who made no such promise. His intensity and permanency will probably scare the pants off of her at first, but there is something mysterious about this man that she will want to get to understand.
She will be late for many of their dates, but he will love her intellectual charm so he will let it go. Her story will change every day and interrupt him frequently, but she is so sweet and her smile is so bright that he lets it go. She will love his deep voice, his intense stare, and silent strength. Little does she know she is his prey. Once a Scorpio man decides he wants you for keeps, you have little chance of escaping. This sounds terrifying to a Gemini, but she won't do much to stop it from happening.
Now that they need to learn to stay together; a task much more difficult. It will drive her insane that he wants to know where she is and what she is doing on a regular basis. She will make him think she is flaky with her ever changing mind about what she wants to do, and who she wants to be. She doesn't have even close to the same amount of self control as this man does. That's just not her. She just needs to know the basics, and he wants to understand things to the core. He will have many lessons he wants to teach her that she will have no interest in knowing. They will drive each other a little crazy.
For a Scorpio man to be truly faithful, the woman that he is with must fulfill him sexually. That may sound unfair or chauvinistic, but with a Scorpio it is not. You see, Scorpios see sex as a way to connect spiritually with the person that they are with. It is not a pastime, or a game that they play. It is much deeper than that. So when the connection is not being made with him it becomes a problem of them not feeling close to the one they love. A Gemini woman does not look at sex like this at all. In fact she is probably laughing at what I just wrote. See to her, true connection is through the mind and through conversation. Here is my question; why can't they meet halfway? I believe that they can. It will take effort, and like I mentioned before, respect.
She is intelligent to know how to fix things when they are broken, and he is intuitive enough to feel how to make things right. They have to WANT to do so. Love can conquer all, and they may just be the couple to prove that.