No, Goldwater heartily endorsed Reagan. I remember him saying at the Convention, from the podium, that if Reagan was not elected, the U.S. might not ever have another presidential election.
When he got older and married a liberal woman, he did flip to Liberalism to a certain extent.
All for show, he didn’t believe it. Reagan at least “believed” in Goldwater in 1964 when he heartily endorsed him, but the reverse was not true of Goldwater in 1980, or 1976 (when he endorsed a damaged Jerry Ford).
He was always married to “liberal” women. His first wife was a huge mover and shaker for Planned Parenthood going back to the 1940s and was a friend and disciple of Margaret Sanger. He was always pro-abortion and sadly lied to the people of Arizona about it, especially in 1980 when his Democrat opponent was to his right.
He was effectively a Democrat in his last decade or so of life, endorsing Democrats for office, railing against religious Conservatives and embracing the radical homosexual movement.