In Meera's story of the little crannogman, if we take the "she-wolf" to be Lyanna, and the "dragon prince" to be Rhaegar, she was moved to tears by his musical performance. If she disliked him, she was pretty much alone in that opinion by all recollections, except maybe people who hate Rhaegar for his role in her death. Even Ned's recollections about Rhaegar don't jibe with the ostensible reputation - at one point, when ruminating on Robert's bastard by a hooker, he doubts that Rhaegar had ever visited brothels. Assuming your sister's rapist was of too fine a character to engage a prostitute is a huge mental leap...unless he knew the man was not a rapist.

Technically, Rhaegar was a statutory rapist and kidnapper (as the original connotation of the former term had more to do with theft than violation), because Lyanna was not legally free to consent to their relationship. She died at sixteen, at the end of a war that lasted a year, so she was likely underage when Rhaegar took her away from her fiance, in addition to the issue of having a fiance in the first place.