hey there
Well first of all there is nothing wrong in.. being worried about that little issue.. there is nothing wrong with you.. at all you dont want the same thing to happen to you.. and its only natural you feel that he may end up doing the same thing to you as he did to them 3 women.. but we all have done things in the past, and he has a point the past is the past, but its also true that the past makes up who we are today, and if we dont learn by our mistakes we can never grow.
if he is good to you.. and shows you respect.. then i personally dont see a problem it would be unfair and time waisting to keep thinking that he may do this or may do that.. i know i have that problem as well. in my relationships.. i always seem to put the way my Xs was to the way my new girlfriend is.. it never works just hurts us both :x
but once again there is nothing wrong with you.. just take each day as it comes and enjoy the time you have together
kind Regards
Faith