A Muslim man has proposed marriage to her, and she committed a sin previously
I now know a Muslim man who has never been married, and who would like to marry me. I am concerned that this is not in his best interest, but I am not absolutely sure about this. For one, our values are presently very similar, and we have much in common. In fact, I have never known anyone so similar to me. However, his life has been somewhat different from mine, and Allah has mercifully protected him from some choices I had to make. What I want more than spending my life with this man is for him to be at ease with his decision to marry me, and to feel that it is religiously correct or permissible for him to do so. Is that possible?
If the man who has proposed marriage is compatible – i.e., his religious commitment is good and he is trustworthy, it is not permissible for you to hesitate to accept him. The doubts and objections that are not based on any evidence do not mean anything, so do not worry about them. If he is as you have described, then do not hesitate to accept. With regard to the previous mut’ah marriage, there is no doubt that mut’ah is haraam; it has been abrogated and it is not permissible to get married in this way. But if you knew that at the time, then you have to repent and ask for forgiveness.