I have a feeling the author doesn't like Udomyon. I hope I'm wrong.
They seem to like
one half of it just fine - the one where Youmu likes Reisen.
I think someone who truly cannot get behind a certain ship at all would just avoid bringing it up altogether, even if it's popular. And it's not like they aren't being paired up - this is the second time Youmu got rejected, but even outside of those two rejections Youmu had another big time L during the sleepover chapter, when she had to ask Reisen for an escort to the bathroom at night because she was too freaked out to go alone. That's three times they were paired together - even if you had a ship you hated and you wanted to prove to everyone it doesn't work - you would only have to do it once.
So: I think the author does love Udomyon - but you're currently reading the kind of Udomyon they like the most: the one where Youmu suffers. That's not even that unusual for actual Udomyon-centered works, like Mamange. Even there, Youmu suffers! It's just how this pairing, or even any pairing that involves Youmu, seems to work out. Youmu doesn't have the smarts, the charisma, or the looks, so the only way she wins romantically is persistence.
It's actually a lovely touch to have Sakuya be the one who's consoling Youmu and encouraging her to keep trying. She thinks it's
good advice - after all, she's now in a relationship with Meiling because she's categorically refusing to accept a version of reality where she isn't. (Sanae, on the other hand, has no excuse. She knows Youmu is going to keep failing, and she's in it for the entertainment factor.)
The big difference between this manga's Meisaku and Udomyon isn't even that one is mutually requited while the other isn't - it's who is the one doing the suffering. Youmu here suffers because her feelings are unrequited, and she actually understands it. Sakuya's feelings for Meiling are (almost completely) unrequited, but it's Meiling doing the suffering because Sakuya refuses to understand it.