Disappearance and consequences
At some time after the tournament, Lyanna was kidnapped by Rhaegar with the help of
Arthur Dayne and
Oswell Whent. The story (as told by
Robert Baratheon) goes that Rhaegar carried her off and raped her. Barristan Selmy is convinced that "Prince Rhaegar loved his Lady Lyanna," though that love sent thousands to their respective deaths. According to
Viserys Targaryen, Rhaegar was simply not happy with his marriage. If Rhaegar was happy with Elia, he would not have needed Lyanna. He once blamed their sister
Daenerys Targaryen for being born too late to marry Rhaegar. A happily married Rhaegar would need neither Elia nor Lyanna. Daenerys, countered that, by the same logic, it was the fault of Viserys that he was not a girl. Because then he would be the sister destined for Rhaegar. Viserys beat her cruelly for her insolence.
Cersei Lannister, who was infatuated with Rhaegar, believes that the
madness led King Aerys to deny
Lord Tywin's proposal of marriage between her and the crown prince; Cersei thinks that if she herself had only married Rhaegar as
the gods had intended, he would have been satisfied in his queen and never have looked twice at the "wolf girl"
http://awoiaf.westeros.org/index.php/Lyanna_Stark