But you must fear,
His greatness weigh’d, his will is not his own;
For he himself is subject to his birth:
He may not, as unvalued persons do,
Carve for himself; for on his choice depends
The safety and health of this whole state;
And therefore must his choice be circumscribed
Unto the voice and yielding of that body
Whereof he is the head.

– William Shakespeare

Hamlet, Act 1, Scene 3. Laertes tells Ophelia that Hamlet cannot marry who he wants to. He is bound by the needs of the royal family and has to marry with the safety and security of the entire country in mind. In other words a marriage between Ophelia and Hamlet is impossible.