Here is a quote of the relevant parts of JSNYC's instructions. I've bolded, italicized, and underlined a few phrases:
If the answer is either yes or no, then the card in the opposing position (position 1 or 2) explains why that answer (the answer it represents) is the wrong answer or simply why that answer was not chosen.
The card in position 3 indicates what could be done or what could happen to change the answer. This could be what the seeker could do to change the answer from No to Yes (or vice versa), or it could be a stipulation on the answer given.
If the answer is neither yes nor no, then the card in position 3 explains why the answer is maybe, or why the question cannot or will not be answered. It is also possible the question simply cannot be answered at this time, and then the card in position 3 could indicate what needs to happen before an answer can be given.
--So the WHY card does give info: what you could do to change your answer, or it could be a condition of your answer.
--The OPPOSING card to your answer explains why that is NOT the answer.
--If you got neither a yes or no answer, then the WHY card explains why it's a maybe, or why it can't be answered at that time, or what needs to be done to obtain an answer.
I hope that helps explain it!
To take a very quick stab at your reading, following the rules of the spread: The Ace of Cups gives you a cursory YES. The Queen of Cups explains why NO is the wrong answer, which I interpret to mean that the appealing qualities of the queen (you) make it difficult for him NOT to fall in love with you!
The Knight of Swords in the WHY position could mean a number of things: if you exhibit the qualities of this knight, you could perhaps make him NOT fall for you. Or maybe it's a condition of your yes answer, meaning that either you or he needs to exhibit those qualities to have the outcome come to pass. Or maybe if a Knight of Swords shows up in your life, something will happen to prevent a relationship between you and Mr. S. The Why card is the most difficult to interpret!!