Not gonna lie, 90% of wholesome manga/anime is ruined by unnecessary fan service not fitting in 🥲
For me it should be in the service of the story and that should be the best way to service the fan as well.
Example:...character stumbles upon someone naked in the shower, I don't like it, not just because is an old trope, but it creates a contrived conflict that just delays the story.
Better Example : Now, this is again silly, but is the first one I thought of, let's say FeMC has a wardrobe problem and needs the MC help, you got your fanservice sure and the cause
could be contrived, but you establish that even in such an embarassing moment the FeMC felt like she could trust the MC enough.
Or a more recent example in Ore no Kurasu ni Wakagaetta Moto Yome ga Iru (Crossing fingers Bear necessities is doing the next chapter)
https://mangadex.org/chapter/d4d58896-3c70-4326-8950-4c232f894c91/23
Negative examples for me would be with Hajimete no Gal,Shishunki na Adam,Maga-Tsuki,Kuro Gal-san ga Kuru!,Sora no Otoshimono,....where the romance is superficial or even non-existant, the relationship are fragile and sometimes can't even be called friendships.
Another example is that you always gotta tie the action to the narrative, see videogames, people might think that plot is meaningless, but would Doom have the same cult if the aesthetics the sound and design were switched to a military shooter, or even a normal scifi without any demons and infernal motif? Doom wouldn't be the same if it was just a single room with one enemy at the time like a firing range, you need all the moving parts..........................
Tl dr: if I can get the same type of content by just browsing fanart or pinups from a pixiv accont, then the story is not worth reading.