No. She is to be your bride not a servant. She is free to leave if she pleases. Perhaps it is not a real marriage if there is so much distrust before you're even married. USCIS will pick up on insincerity at the interview. I'm not sure what you mean by "more responsible" but she is free not to marry anyone she wants.
The letter of intent has to include a very detailed history of your relationship. If you are not sincere about the marriage it will come out in the letter of intent.
This response does not create an attorney client relationship and is for informational purposes only. Before acting on this information you should discuss your problem with an immigration attorney.
I actually completely agree with Attorney Dore. I could not have said it better myself.
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