You’re Astolfo, and in this scenario, sieg is female, and you just gave her a letter confessing your love to her

Sieg: “Astolfo, I only like you in a friendly way, not romantically, your a servant, a summoned rider, someone to fight for me, not to love. your also a friend, but nothing more, imagine it like this, your like a best friend to me just a best friend.”

She sounded cold while saying this, not having much empathy while rejecting you; sound more matter of fact.