"No, you can't come," Nina said
"Ni, I'm the reason for breaking this engagement, I think I woo an explanation for him," Erik said
Yes, Erik doesn't want Nina to suffer and explain herself to someone. Though he had differences with Leo but Erik knows Leo can't stoop low by marrying someone who doesn't love him but also he want to explain things and break this engagement very smoothly. At the same time, he wants to go everything smoothly not because he can't fight with Leo but because he don't want to suffer Nina because of their conflicts.
"Erik, it's not your fault okay, I don't want Leo to misunderstand you," Nina said
"But"
Cutting him off Nina said, "No, I don't want to be the reason for your misunderstandings, I will explain him and if I feel the situation is out of control I will call you okay."
When Erik didn't say anything for a long time Nina sighed and said "Please babe, let me meet him and explain things."