You're just now getting into Johnny and Winona, Alison?
I had to live through it as it was happening in the media. Johnny had a tattoo on his arm that read "Winona Forever," but after the breakup he had it changed to "Wino Forever."
I have no idea if they had a song that was like a theme song for them because they never spoke about it, but I do know that Winona had a penchant for dating rock stars and co-stars. Before Jonny, she dated Christian Slater after they worked together on Heathers, and also dated Rob Lowe after starring in a movie with him. Afterwards she dated some rock stars like Beck and Soul Asylum frontman Dave Pirner. She also called Keanu Reeves her "husband" after they worked together on Dracula.