He was only 14, and she was only 12 when they were married. He died only 3 1/2 years later, when they were still very young.
She was unhappy, but after a few more years she might have become happier with her position. If he became determined to beget an heir, she might at least submit.
That's unknowable. Why did he abdicate? No one knows, apparently. And he lived over 20 years longer. There's a theory that he hoped to gain the throne of France instead of Spain; but that wasn't on the books IMO.
Suppose that it was his reason, and that the plan fell through while Luis was still a minor. Would Phillip revoke his abdication? Could he do so? Would Luis consent? What would be the role of Elizabeth Farnese?
Scenario: Luis lives. Over the next four years, he becomes accustomed to being King, and Louise to being Queen. Both of them come to resent the influence of Elizabeth, and become reconciled against a common foe.
Meanwhile Philip discovers that his Spanish abdication doesn't restore his French claim. Oops. He tries to revoke his abdication, spurred by Elizabeth.
But Luis has been King for a while. He has his own coterie of favorites and ministers who would be displaced by the return of Philip, and Elizabeth's court faction has made enemies.
Luis refuses to step aside for his father. There is a bitter split in the court, but Luis is the King, and possession is nine-tenths of the law. In one of the weirdest episodes in European history, ex-King Philip and Elizabeth are exiled to France.
The are two schools of thought on why he abdicated. One theory suggests that Philip V, who exhibited many elements of mental instability during his reign, did not wish to reign due to his increasing mental decline.
[9] A second theory puts the abdication in context of the Bourbon dynasty. The French royal family recently had lost many legitimate agnates to diseases, making the lack of an heir and another continental war of succession a possibility. Philip V was a legitimate descendant of Louis XIV, but matters were complicated by the
Treaty of Utrecht, which forbade a union of the French and Spanish crowns. The theory supposes that Philip V hoped that by abdicating the Spanish crown he could circumvent the Treaty and succeed to the French throne. I got this strait from Wikipedia but it sounds pretty true.
I also found three instances of having an abdicated King, two from Spain itself. The first would be a contemporary of Luis I: Victor Amadeus II of Sardinia. He abdicated in 1730 after marrying his mistress. In 1731 he decided he wanted to return to the throne and told his son of his decision. He was promptly arrested and placed under house arrest untill his death a year later. The second instance happened in the nineteenth century: Carlos IV of Spain. Carlos abdicated in 1808 to save his favorite minister,Manuel de Godoy, from being killed in an uprising in Aranjuez. His son Ferdinand became King but was deposed by Napoleon. The Spanish royal family was held prisoner in France for several years but Carlos was freed in 1812 after accepting a pension from Napoleon. He and his wife Maria Luisa of Parma died in Rome in 1819. The third was Queen Isabella II. She was deposed in 1868 but didn't abdicate her rights until 1870 in favor of her son, Alfonso XII. She spent the rest of her life in France, except for short visits to Spain.
So the best bet about Philip V would be he decides he wants to retake the throne and is promptly arrested, along with Queen Elisabeth Farnese. They are either held in Spain or deported to France, where Philip used to be a Prince and would be the next highest ranked at court, as France would continue to call him King, sort of like with James II and his wife Mary Beatrice.
As for Luis I and Louise Élisabeth, I would guess that there would be a reconciliation. They were very young and I forgot to take that into acount. After all Louis XVI and Marie Antoinette were married for 8 years before Madame Royal was born.
I wonder if Luis would intervene in Italy in favor of his brothers? It could go either way. Wanting to advance the House of Bourbon vs. helping the sons of the hated Elisabeth Farnese.
http://en.wikipedia.org/wiki/Wikipedia:Citation_needed