http://www.mangago.me/read-manga/ore_no_kanbotsu_chikubi_ga_senpai_no_shitapi_de_tachimashita/ the not announcing relationship happens a bit later
feelings about ex:
http://www.mangago.me/read-manga/fools/
http://www.mangago.me/read-manga/kakkou_no_yume/ this one is sort of in that vein but its kinda complicated lol
http://www.mangago.me/read-manga/inner_beauty/ this one the guy is dating his ex girlfriend but they eventually start liking each other
i hope these help a little?
Watch tharntype(it's a thai bl serie and it's really good. It's also foing to have a second season this year) for the manga I can't remember any rn
Yaoi manga where one of them gets upset because the other doesn’t want to announce their relationship?
Or the other still has lingering feelings for his ex and it causes a fight. Stuff like that