Marina Abramović is renowned for her lifelong dedication to performance art, but she made some of her greatest work with her fellow artist and onetime romantic partner, Frank Uwe Laysiepen (best known as Ulay). The two were born on the same day and met on their birthday in 1975. Ulay was making art about gender, twinship, and male/female duality, and in Marina, he found his creative and personal other half. Even before she knew what body art or performance art were, Marina was creating it, often making herself very vulnerable in the process. She saw her body as a canvas and recognized its potential to make confrontational work, like “short, intense political pieces where I am plunging the knife between my fingers and cutting the communist star on my body.” With Ulay by her side, she was able to create art that spoke to the duality of their relationship. Their artworks flipped between romantic and threatening; platonic and aggressive.

One of my favorite pieces that they created together is Imponderabilia, which they performed during the 1977 performance festival at the Galleria Comunale d’Arte Moderna e Contemporanea in Bologna, Italy. Marina and Ulay stood naked against either side of the door frame at the entrance to the gallery. To get inside, visitors had to squeeze sideways between their two bodies and choose to face one of them, while turning their backs to the other. You might know this as one of the works that was recreated by performance art students at the Museum of Modern Art in New York and featured in the documentary Marina Abramović: The Artist is Present.

After obsessively making art and a life together for 12 years, they placed themselves at either end of the Great Wall of China and performed a piece called The Lovers: The Great Wall Walk. It was originally supposed to end with the pair meeting in the middle and getting married. Instead, after three months of walking, they embraced and went their separate ways. They didn’t see each other again for seven years. “He invites me over sometimes, grills a little steak for me,” Marina told her friend Laurie Anderson a decade after The Lovers, “but there is still a lot of pain from my side. It didn’t really finish well.”

In the most famous scene of The Artist is Present, Ulay surprises Marina by sitting across from her during her exhausting marathon performance piece after decades apart. I like to think that that wasn’t just two ex-lovers reconnecting through their shared medium, but also an act of closure. When Ulay took a seat across from Marina in the atrium in the Museum of Modern Art, he experienced her commitment to her art the way the rest of her audience does, where we see, are invited into, and are given the chance to contribute to it.