@MacMeaties
do you mean you'd prefer if there is a male rival to the male Mc in a shounen/seinen romance manga ? , if so, there are LOTS:
TAKAHASHI Rumiko's manga: ranma 1/2 , innuyasha (kouga) , etc.
seo kouji's manga: suzuka, Kimi no Iru Machi, etc.
SASUGA Kei 's manga: domestic no kanojo , good ending
yesterday no waratte
ichigo 100%
onani master kurosawa
Ran to Haiiro no Sekai
Yamada-kun to 7-nin no Majo
school rumble
Nana to Kaoru
Hetakoi
billionaire girl
Destroy All Humankind. They Can’t Be Regenerated.
nana to kaoru
unbalance x unbalance
genshiken
of course , female love rival for the female MC are still more common in shounen/seinen , but male rivals clearly
do exist in shonen/seinen manga , and the male rival sometimes even win.
for shoujo/josei: there are lots more male rivals for male MCs: around 1/2 of shoujo series have at least one male rival