When 16 year-old Richard first asked Edward permission to marry Anne Neville, Edward IV refused, saying that he’d reconsider if after a year, Richard still wanted to marry her. Once the year passed, Richard again asked Edward, who then agreed. Before Richard could act, the Lancastrians overthrew Edward and the crown returned to Henry VI. Edward and Richard went into exile in Burgundy. During this time, Warwick married off his daughter to Henry VI and Margaret of Anjou’s son, Edward. About a year and a half later, Edward retook the crown and captured Henry VI. Henry’s son and Anne’s husband had been killed on the battlefield.
Thus, in 1471, Richard, now 19, renewed his request to marry the recently widowed Anne Neville. Although Edward agreed to the marriage, George—who by then, had custody of Anne—argued against it. Edward, found in favor of Richard. George, refused to turn Anne over to Richard and hid her from them. In effect, this strife made headline news, for it is documented in the Third Continuation of the History of Croyland Abby (r3.org/bookcase/croyland/croy6.html):
...After, as already stated, the son of king Henry, to whom the lady Anne, the youngest daughter of the earl of Warwick, had been married, was slain at the battle of Tewkesbury, Richard, duke of Gloucester, sought the said Anne in marriage. This proposal, however, did not suit the views of his brother, the duke of Clarence, who had previously married the eldest daughter of the same earl. Such being the case, he caused the damsel to be concealed, in order that it might not be known by his brother where she was; as he was afraid of a division of the earl's property, which he wished to come to himself alone in right of his wife, and not to be obliged to share it with any other person. Still however, the craftiness of the duke of Gloucester, so far prevailed, that he discovered the young lady in the city of London disguised in the habit of a cookmaid; upon which he had her removed to the sanctuary of St. Martin's....
Richard and Anne married * and moved to Middleham Castle where they resided until Richard was named protector and then became England’s king.
* The exact date of the marriage is in some dispute, although now it is generally thought to have occurred in April of 1472.