Guys...do you think a man with promiscuous past will stay faithful after he is married?

Would he be able to stay with one woman, if he never had a real relationship and always had multiple girlfriends? This man is my husband and he says he just got tired of that life and and wanted to settle down and have a home and family. Now he enjoys married life and he has no desire to go back to that life style. I always wonder if someone with his background would really change and become a loyal family man. Or, is this what he tells me to put my mind as ease, but secretly he is still the same.