What is the name of the book? its an older book. abt a grl lookn for gma and is mistaken 4 a prostitute.?

She is on a boat and gets mistaken for a prostitute and then she falls in love with this guy and he thinks she is a prostitute and fakes a wedding and then has with her and throws change at her. later in the book she finds her rich grandmother. and the guy gets sick and the woman finds out and still takes care of him even though he was a . in the end they meet on the boat agian and they fall in love. any clues to what the name of this is. i would really appreciate it. thanks.