The Treason Act 1536 (28 Hen.8 c. 18) was an Act passed by the English Parliament during the reign of King Henry VIII of England. It made it high treason to marry or become engaged to the King's children, sisters, paternal aunts, or his nieces or nephews without the King's written permission, or "to deflower any of them being unmarried." It was also treason for any of the same relatives to participate in such treason.
The Act was repealed by the Treason Act 1547 in the first year of the reign of Henry's successor, Edward VI.
References
Treason Act 1536 Wikipedia(Text) CC BY-SA