All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His Slave and Messenger.
First of all, we thank you for contacting us and your resolve in consulting us. We ask Allaah to help you do what He loves and is pleased with. We ask Allaah to bless you with a righteous husband who will be a comfort to your eyes and who you will be happy with in the world and the Hereafter.
As regards your fiancé, if he is a religious man and has good moral conduct, then you should not hesitate to accept his hand in marriage just because of a small mistake. However, if he is not a religious man and does not have good moral conduct, then one has to make sure about him before marriage because separation during engagement is easier than separation after the marriage contract or after having children.
Indeed, Allaah, The Most Wise, has guided us to what a woman should consider when choosing a husband: religion and good moral conduct.
Finally, it should be noted that before the marriage contract the fiancé is still considered a non-Mahram to his fiancée; they are not permitted to be in seclusion with each other, or touch each other or the like, and talks between them should be limited to what is necessary. For more benefit, please refer to Fatwa 86143.
Allaah Knows best.