The ellipsis...

You think it reads as casual, mellow, "like, whatever, dude... It's all good..."

But actually it reads as an eye roll, impatience mixed with passive aggression, unwillingness to be direct. It sucks to receive an ellipsis. End your sentences, and do so confidently, so people will know what you mean.

“In prose and lyric, especially from someone with a practiced grasp of language, the ellipsis serves a purpose. In emails and text messages, it should be regarded as the fastest way to undermine intent.”
— Evin Wolverton