In Robert Burns' poem, reading between the lines (in the Scots dialect), one can see the subtext in the story.
The speaker refers that should the lad go to the speaker, the lad's parents and everyone else would "go mad." This could mean that they would be angry or crazy--which would happen if they discovered he was involved with another young man, but the speaker reminds the lad that even in this case, his "Jeanie" (perhaps his sister) would come along, perhaps to make it look proper, as if Jeanie is going to see the speaker, and the lad is there to chaperon.
The speaker tells the lad that he must observe caution and come warily, secretly to court him, so that no one can see him, coming through the back gate and up the back stairs. He urges the lad to travel as if he is not traveling to the speaker; but that with a whistle, the speaker will come to the lad.
In the next part, the speaker instructs the lad that should they meet in church or at the market, the lad should pass by as if he cares not at all for he speaker. He asks the lad to give him a wink, but to do so as if he wasn't even looking at the speaker. And a whistle will be a signal to the speaker from the lad.
The speaker next tells the lad, if necessary, to vow and deny that he cares at all for the speaker, and even scorn his good looks a little, but he asks him, too, not to court anyone else, even if the lad is just joking, for the speaker is afraid "she" will steal the lad away from him.
This last line seems to be the strongest of the subtext in that it uses the pronoun "she." The speaker fears that the lad might pretend to like a girl, and the speaker fears that she will steal the lad's affection away from the speaker.
If the speaker were a woman, why would the lad courting her need to be done in secret? There is never any mention of differing social status, poor reputation, or problems between their families. There is no indication that the speaker is a married woman, either.
The idea of the whistle also provides a sense of the secretive in that it is a private signal between the two, rather than the carrying of a tune, for instance, or calling to a horse.