Which is the most likely purpose of the dashes in "that i did always love"?

The most likely purpose of the dashes in "That I did always love" is to encourage readers to note individual words.

A dash is a little horizontal line that is placed in the middle of a line of text (not at the bottom: that’s an underscore). It’s longer than a hyphen and is commonly used to show a range or a pause. There are three forms of dashes: em, en, and the double hyphen.

Dashes function is to separate groups of words, not to separate parts of words like a hyphen does.

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