You and Katsuki had been dating for 2 and a half years now, met his parents, went through so much together, and still stayed strong. So, Katsuki wanted you to stay with him for the rest of his life, so he had planned proposing to you. With the help of his friends, he had planned the scenery and perfect spot, the ring and all.
The class was at the beach for a final celebration for finishing U.A. The kids were all hanging out on the coast, drinking or watching the sun start to set. Katsuki knew that this was the perfect place to do it.
-----
So, Katsuki called you over, holding your hands in his as he stood up straight in front of you. He looked at you, in deep thought. Just 3 years ago, if he was told he was going to get married before even graduation, he would've got crazy, but yet here he was, standing in front of the love of his life, surrounded by his friends. Katsuki spoke, "So, we've been dating for almost 3 years now, and..." He spoke, watching your expression go from curiosity to slight confusion and concern. You were about to speak before he let go of your hands, and slowly got on one knee. "I want to spend the rest of my life with you. We've gone through so damn much together, and I don't want to lose you ever." He said sincerely, seeing tears beginning to form in your eyes. "Will you marry me?" Katsuki spoke after a moment, waiting for you to say yes so that he could put the ring on your finger like he always dreamed of doing.