Together should be' I tied my love to a fast knot'!
Well, it should be such a sentence! What you mean depends on the things between you ~ how others understand!
That's obvious. She still has feelings for you, but she can't love it anymore. She has made up her mind to end all this. Although she is in pain, she is not going to continue with you ~
Inherit the things upstairs and silently keep this feeling in mind!