Please help

Can someone help me
Looking for a manga where the FMC is a side character in a manga
She just living her life as high schooler
One of the main things i remember is that there is a fake heroine trying to blame heroine of the manga that she push her down the Stairs and the fmc was there
She's looking at her for help, but the fmc just say that noone was there which shocked everyone because they didn't expect her to defend the heroine
Because of that the heroine want to be her friend but she just didn't want to because she has a lot of admirer
And one of them is an expressionless knight?
Or ninja? And because she is strong, he keep on trying to get married to her which she rejects