Well I do have to agree with Senpai, if you like or love someone you can confess to her/him it's your right to do so, but one thing for sure is you can't force your like/love to someone the other party have the right to choose, it will be a huge turn down and you will be just a bother, please give the opposite party the choice to choose and consent.
From the way how Kouhai-kun act up until now maann if it's not a manga world I'm sure it won't work (unless both of them head over heels to each other but in this case no), the way it's going right now is unhealthy relationship.
And to answer the chapter title, yes you're a bother she already said no, you should respect her decision if you really love her, even when later she regret her decision.