What exactly is a relationship like with a prince and what is how princess and how could someone be one?

A prince is the term used when referring to a male offspring of a king & queen or the heir/heiress to the throne the children will have the same applies to the daughters. You may become a princess by marrying a prince or princess but you may not if you are a commoner however you maybe given a title each royal family house has different rules in terms as to weather you can be addressed as a prince or princess. There are many disposed royals as well as pretenders to thrones since many countries abolished or got rid of their royal families. You will not be able to recognize a prince or princess as it is very unlikely the walk around in royal regalia. Prior to unification countries like Italy, Germany & France had different royal houses. So there are many royals that you may not be aware of. The same applies to Russia which has very strict rules as to whom can be a king/queen & whom can marry into this establishment!( once the legitimacy issue is resolved a royal family may emerge). Hope this answers your questions. Anyone can be called a prince or princess as a term of endearment!