I understand where you're coming from. There's this long lack of communication. It was a bit hard to read sometimes because Yuchun just doesn't explain his plans and expects Geonwoo to like it. There's no warning that he plans to "spice things up" and Geonwoo stays confused for a majority of the time about his motives. The story was short so maybe that's why but it felt like Yuchun rushed into this and didn't think about it at all. Luckily, they seem to have an overall good relationship and I'd like to think this is something that could happen, your partner wants to try something new, rushes into it, and doesn't really know exactly how to properly communicate the plan so it's something couples have to talk to each other about but Yuchun accepts that Geonwoo doesn't want to use the toys in the end, so I think it was okay in the end.
I felt like gunwoo was kinda being a bit manipulated at times but idk