Carly Simon is a musician who had a notable rivalry with fellow folk singer Joni Mitchell. Their beef wasn't over music or anything like that. Their beef was over the guy standing next to Carly Simon in this photo. That's James Taylor, who was also a musician. Both Simon and Mitchell loved James, but Carly ended up snatching him up in the end. The two of them got married in 1972.
The two of them had two kids together, but they eventually separated a little bit over a decade later in 1983. Joni Mitchell wasn't around to step in and reclaim her man, unfortunately for her. I've never been part of a love triangle like that. I'm sure it sucks for the two people competing for the other person, but it must be pretty cool to have two people who want you so badly that they'd fight each other for you.