Is it okay to ask why when getting a no?

I am starting out in the wedding business and have 5 booked already this year. At the start of the year it seemed like every inquiry that came in was genuinely interested and booked with us. The last 5 or 6 the next two months have all gone with someone else. I know it’s part of the business but I’m genuinely curious as to what turned them away? is it unprofessional to follow and ask?