Just to warm you that marrying a croatian man and even getting a croatian passport you won't become a citizen of EU, because Croatia is not an EU member. Even "better", you would still need a visa for travelling to England and at UK embassy in Zagreb they are likely to treat you as a criminal when you come to apply for visa with a croatian passport. And at almost every border in EU they will treat you bad, with an arrogant and rasistic attitude.
I suggest you stay american. We all people are very much the same poor creatures, but you got much more luck and easier time in surviving as american than we croatian got it on this small piece of land over here. But of course I also wish you to find a croatian man of your dreams. Men there, though not always practical, have honest hearts and are capable of feelling deep and of respecting women for what they are and stand for.