Irina, ======= Will you marry me? This is a direct question. It is also the customary way to propose marriage to a woman. Examples Will you come to the party? ..... an invitation with a response expected. Will you be there tomorrow? Yes or no? ========= Will you be marrying me? It is a polite inquiry about someone else's future plans without an attempt to influence the listener's decision. It is a formula of politeness, which would be absurd or humorous if used in this context. Examples Will you be coming to the party? ...What are your plans? Will you be paying for this by card or by cash?

"Will you marry me?" is a question/request. "Will you be marrying me" would only be used for specific questions like, "Will you be marrying me for love or for my money?" or "Will you be marrying me in a church or at the city hall?" The continuous form usually means that something is continuing, but you only marry a person once, so it really can't be used in this case, apart from the exceptions I noted above.

Will you do it? = request or command Will you be doing it? = yes/no question

Thank you very much!