@genericlinic I'm not sure but Yuuya is his given name and in Japan it's kind of a big deal calling someone by his given name since it means you're pretty close (like lovers for example) so since she starts calling him that even when speaking of him to someone else when he isn't even there that means she is pretty used to call him that. So when her colleagues hear her calling that I guess they thought it was cute or something because like I said it means they are very close to each other.
@Abeliss95 no, just the end for this chapter. Some chapters have continuation like the ex-bf one, so it's to be continued instead of the end. Don't worry this manga still has ton to talk about.