All four of the children of Henry VII & Elizabeth of York who lived to maturity initially made marriages of state. Arthur & Henry both married Catherine of Aragon (who was slightly older than them both); Margaret was sent to Scotland at age 14 to wed James IV (who was more than twice her age). Mary was packed off to France to marry Louis XII (methinks it was XII, & he was more than THRICE her age).
And then a strange thing happened while trotting along the bridal path, for royals....
First, Mary Tudor made a clandestine marriage in France with Charles Brandon, Duke of Suffolk, largely regarded as a jumped-up commoner by the "old" nobility (much like the Howards & Boleyns were). Brandon's matrimonial career was "checkered" & ended up being sorted out by the Vatican after he wed Mary. Briefly, he was betrothed to Anne Browne, with whom he had a daughter before exchanging marital vows, & then ran off to marry her wealthy aunt, Margaret Mortimer, instead. That was quickly annulled on the grounds of consanguinity, & Brandon then went back to Anne & finally married her; they had 2 more daughters before her demise. At the time of his marriage to Mary, he was betrothed to his ward, 9-year-old Elizabeth Grey (who was younger than his eldest daughter by Anne). Meanwhile, Margaret Mortimer was loudly protesting that their union had never been annulled....hence the untangling required by Rome to eventually pronounce his marriage to the "Tudor Rose" the legal & valid one. This was especially important because not only was she the king's sister, who could not be seen to living in an "adulterous liaison", but Mary Tudor by that time had given him a son & heir at long last, Henry (of course), who the Brandons definitely did not want to see bastardized.
Then Margaret Tudor, following the death of James IV at Flodden, married Archibald Douglas, Earl of Angus, in a vain effort to consolidate her precarious position as Regent for her son, James V (o those troublesome Scots lords; Margaret needed strong allies from among them if she & her son were to survive). Of course this led to the usual outrage & hijinks, with Margaret being forced to cede her position & her physical possession of her 2 surviving children by James, & eventually fleeing to England for her brother's help & support (sound a bit like MQOS, Margaret's granddaughter?). Although Margaret was well-received by Henry, he (whose matrimonial career would soon become notorious) was outraged at her notion to divorce Angus & allegedly instrumental in their reconciliation. Angus was a miserable spouse who openly flaunted his mistress, whom he kept on his allowance from his wife. Margaret was able to effect a remarkable coup d'etat against the Scots lords & regain her position, & eventually got her divorce from Angus.
However, she then developed an attachment to Henry Stewart, Lord Methven. Methven, however, proved about as charming a spouse as Angus had, & Margaret unhappily was unable to obtain a second divorce, tied to Methven until her death of a stroke in 1541.
Then there's Henry LOL whose matrimonial career is the stuff of legend. His other marriage of state, that to Anne of Cleves after Jane Seymour's demise, was persuaded upon him by Cromwell as a way of thumbing the Tudor nose at the Catholic heads of state in Europe by allying England with the Protestants. However, he married Anne Boleyn, Jane, Catherine Howard, & Catherine Parr "for love", disregarding his council's wishes for a foreign alliance of greater benefit & dismantling Catholicism in England because Rome was not as lenient to him in divorce matters as it had previously been to his sister Margaret.
It's highly unusual in the annals of royalty for a family to, having done its duty with a state alliance once, then disregard the advantages of such & rush to the altar with a parade of commoners.
What made the Tudors so different from the rest of the crowned heads of Europe? Did Mary's determination to marry Brandon precipitate her brother & sister to throw away convention & follow her example? Was Henry perhaps jealous that his sisters were able to marry where they pleased? Was he furious that Margaret could obtain a divorce merely because she & Angus did not suit, while he could not get Rome to cooperate with him in the matter of Catherine's inability to give him a son? Was he driven to his actions seeing that his sisters had sons, while he was denied one? Opinions?