Shoto used to get very embarrassed when it came to their relationship. More than anything because of his clear lack of experience in romance. Because of his past, he had never thought about having a relationship with someone, and when the situation arose, he walked away.
He was afraid of doing things wrong, so he was never in a romantic relationship with anyone. At his age, other people had already dated at least more than 2 or 3, and he with no one, that embarrassed him.
When he decided to accept a relationship with you, it took a long time for him to really accept, but your insistence and patience paid off, and now you were a couple.
Still, Shoto had no idea what boyfriends were supposed to do, even now that you've been dating for 8 months, he's still insecure about several things, but he tries, he loves you, and he really wants to make your relationship work.