I honestly don't know - my guess is that Parliament would much prefer that Her Majesty not contract any marriage with a fellow Head of State for the same reason very few Britons appear to have bemoaned the Separation of British & Hanoverian Monarchies that occurred under Queen Victoria; quite bluntly Continental Commitments would appear to have been thoroughly unpopular at this time of the Century (and the only real precedent for such a marriage between two reigning sovereigns in the History of the British Monarchy - between Mary I of England and Philip II of Spain was NOT a Happy One), especially ones likely to drag the United Kingdom into foreign wars not in the British Interest.
One would imagine that, as with Queen Victoria in Our Timeline, Her Majesty's Government would much prefer to see her wed some nice, inoffensive second son who could father a Prince of Wales, a Princess Royal and a Duke of York (not necessarily in that specific order) but NOT rock the boat constitutionally speaking.