And that is exactly correct. Once they "obtain that world", they will not be courting and marrying someone, since that time has passed. The marriages will have been solemnized and established before then.
Notice the verse does not say what you imply: "they which shall be accounted worthy to obtain that world, and the resurrection from the dead, are not married" In reality, the scripture uses the verb "marry". That word refers to the action of getting married, not to the state of being married.
If we are to believe your interpretation, the ultimate goal of eternity is a massive group divorce. That sure doesn't jive with what I understand of happiness and the importance of the family.
You need to read the context. The question is "Which man is her husband?". Jesus responds "There is no marriage in Heaven so none of them are her husband". Marriage is an earthly institution. When we get to Heaven, no one will be subject to anyone but God ie "Wives submit your Husband as to the Lord".
Some scholars believe the ultimate question was "Who will have sex with her?" and the answer was "There is no sex in Heaven".
That a ludicious interpretation of the Scripture I quoted!