Syd's poem looks back on a small, tender ritual: staying in on Friday nights to paint with someone close. Instead of heading out, the two of them make their own evening. The speaker watches the other person pull their dark hair into a messy bun, and the detail feels affectionate and unguarded, the kind of thing you only notice about someone you know well. They sing as they paint, and the scene feels relaxed and unselfconscious.
The last line is the heart of it. They paint "the sunrise of a rainy morning," an image that blends gloom and hope, and they "spill our thoughts onto canvases," as though the paint is a way of confessing what they can't easily say aloud. The past tense ("we would paint") suggests the speaker is remembering these nights, so the mood is warm and nostalgic, with perhaps a faint ache underneath. It's a gentle portrait of closeness, creativity, and ordinary time that now feels precious.