Oh I'm so glad you asked. If 2D singing "I will always think about you" while a giant picture of Murdoc is projected behind him on stage, if writing an album full of sappy loves songs about loneliness and missing somebody while Murdoc is in jail isn't canon I'm not sure what is. Look at this page from 2D's journal. He doodled scenes from the Stylo MV around Souk Eye's lyrics. It's clearly about Murdoc.>If loving you's a felony now than I'm a renegade
Plastic Beach, or more specifically On Melancholy Hill, Broken and Empire ants, made it obvious back then that Murdoc was obsessed with 2D, but The Now Now has confirmed that the feelings are returned.