Both of those assertions are debatable. Abortion wasn't an issue in Lenore Romney's Senate campaign. We don't know that Mitt Romney was angry about Reagan and conservatism to the point where he ceased to be a Republican.
Like a lot of people, he may have been trying to figure out where he stood politically. Harvard and Boston probably pulled him in a liberal direction, but his main concern in those years was money-making.
As a Romney devotee, you still need to accept facts
Romney was born into politics, at the Governor and presidential level.
Romney was political in 1979 and rejected the GOP that chose Reagan.
Is Romney lying? Is Romney a pathological liar?
Romney says that his family became pro-abortion in 1963.
“Many, many years ago, I had a dear, close family relative that was very close to me who passed away from an illegal abortion. It is since that time [1963] that my mother and my family have been committed to the belief that we can believe as we want, but we will not force our beliefs on others on that matter.”
“I believe that abortion should be safe and legal in this country; I have since the time that my mom took that position when she ran in 1970 as a U.S. Senate candidate,” Romney said
“My position has been the same throughout my political career, and it goes back to the days of 1970,” he said. “There was a woman who was running for political office, U.S. Senate. She took a very bold and courageous stand in 1970, and that was in a conservative state. That was that a woman should have the right to make her own choice as to whether or not to have an abortion. Her name was Lenore Romney, she was my mom. Even though she lost, she established a record of courage in that regard.”