You can inquire about it first and learn about the details of your senior sister from the side. Do you have a boyfriend? Do you realize that you are waiting? After fully understanding the relevant information, you will have a clearer choice.
If you really have no confidence, no confidence, or your sister's heart already belongs to you, then you can also bury this feeling in your heart and keep this secret love until graduation. Everyone has had a secret love experience in his life, which is also a very wonderful experience and a precious memory of life.
By the way, my personal experience. I once had a crush on a senior in high school, one grade higher than me. Although it is not a beauty queen, it is particularly attractive. She not only studies well, exercises well, but also has a good temperament. We also live in the family courtyard of a large state-owned enterprise. No matter at school or on the way home, as long as I see her, I always feel sweet in my heart. I often follow her far away and love her secretly. At that time, I was still a very shy boy and never wanted to express my feelings. Even though I have clearly felt that my sister has discovered my affection for her, she often smiles at me, and so-called eye-catching things happen from time to time. Unfortunately, two years later, my sister was admitted to the philosophy department of Peking University, and later went to the United States. This secret love has become a beautiful memory in my heart forever.
What's there to struggle with? If you like someone, express it bravely. Don't you think it's too scary to keep it in your heart? How do you know if you will succeed by doing nothing? Confess to your senior sister. Only by confession can you have the opportunity to hold hands with your senior sister. If you don't confess, you have no chance at all, only a secret love.