I love how these stories have developed from Marisa x Reimu having Alice as a third wheel, to adding Yuyuko x Youmu into the stories, and then making Marisa and Youmu get along because they are in the same predicament trying to improve their relationship with the one they love, so they feel and share the same worries.
But then in "Gathering Spring" Youmu and Marisa almost fell in love with each other, Marisa was able to just forget about it while Youmu is still conflicted about it. I wonder if future works from the author will continue with Youmu's struggle to view Marisa as "just a friend".
...And Reimu is always totally aware of everything that's going on and she just rolls with it to tease Marisa XD