Hi Diana,
I know several couples that have an big age gap between them and have wonderfull relations and I know several others that are in the same age and have bad / poor relation so it all depends on the people involved (mainly how matured they are). It can easily be that he is 13 years older but less matured than she is. Let us be honest, it also depends on the case as well: A rich guy can easily get a young girl (he wants sex and she wants his money) that will be totally different from relations based on fure love. If you love him and if you get along with him than don't worry too much about the age gap, it doesn't mean much and shouldn't effect your realtions. True love will enable you to overcome all difficulties (not only age gap). As far as I remember you have a bigger problem than the age gap....
Best regards,