Jesper sighs because obviously he knew she was going to say that. And if he didn't need to hear it, he wouldn't have brought it up in the first place. Inej is always honest with him. He can lie to most people, but not to her. "Even I wasn't sure if I had this much space in my heart for everything I felt. And I'm me."

Meaning that Jesper wasn't sure he could maintain so much love and relationships at the same time, despite it feeling so very natural and easy for him. Because feelings are complicated. And yet it only showed him he was right. Each person he takes into his heart doesn't take a piece from anyone else, it's just that he grows in the space needed.

But that's Jesper. People would expect him to be able to do this. For Wylan, it's different. "After everything he went through with his dad and feeling like he wasn't good enough or chosen, I don't want to be another person to make him feel that way. Like he isn't special." And he is special to Jesper. Wylan will always be important to him. He's been without him all this time and yet he's never been far from him.