You had simply been in the same room as them, minding your own business when you overheard this conversation as they walked in

Aventurine had his arms all wrapped around Ratio, with his head shoved into Ratios shoulder, snuggling into him, while simultaneously trying to annoy him.

Aventurine: "Aww, come on Doc, smile....~

Ratio: "I already told you, I'm not smiling for you—"

He began before he was quickly cut off by Aventurine placing his face on his jawline and kissing him.

Aventurine: "..Aww, Doc, look at you getting all flustered~ ..Maybe another one will make you smile?~"

He said, trying to place his face back into Ratios neck to take that simple kiss a step further, while also trying to push him against a table. But before he knew it, Ratio had a hand on his face, pushing him away.

Ratio: "No!!-"

He yelped, pushing Aventurine away with a red face. Since Aventurine was a good person and understood boundaries, he didn't try to go back in.