A cup carried at walking pace
The horse is white and it is not galloping. Its front hoof is lifted in a slow, formal step, and the rider sits easily with a cup held out in front of him, level, offered rather than drunk from. Small wings sit on his helm and at his heels, and his surcoat is patterned with fish. Behind him the ground is dry and bare, and a river runs across the picture towards distant hills.
Two details do most of the work. The cup is extended towards nobody visible, which readers take as an offer made before there is anyone to accept it. And the river is the only water in a dry landscape, so the feeling the card describes is real but narrow, running in one channel through country that does not otherwise support it.
Upright and reversed
Upright, the keywords are romance, idealism and pursuit, and pursuit is the one that gives the card its shape. This is a feeling being acted on rather than merely held. An invitation, an approach, a piece of writing sent, a journey made for a person. The tradition reads it as sincere, and the sincerity is not in doubt at any point in the card.
Reversed, sincerity is still not the problem. The failure is that the feeling has become a story the rider is telling himself, with the other person cast in it. That is where the reversed keywords come from. Fantasy, when the story stops matching anyone real. Inconsistency, when the rider moves on once the story loses its shape. Jealousy, when the story is threatened by a person behaving as themselves rather than as a character in it. All three follow from the same root, which makes this reversal easier to read than most.
Where knights sit, and what water adds
The knight is conventionally the court rank that carries the element outward and in motion, one step below the king and queen who hold it. Knights are therefore read as the element in action, and usually as the element without much moderation, which is why every knight has a characteristic excess attached to it.
Water is the suit of feeling, attachment and what matters to you, so a knight in water is feeling in motion. Compare the same rank in air, where speed produces argument, and the difference is the whole point of the court system. The card data here gives an element and no zodiacal ruler, so water and the knight's rank are what supply the reading. Many readers treat the courts as manners of acting rather than as people, which works well for this card, since the romantic gesture is something anyone can be in the middle of making.
What it asks
The useful question is not whether the feeling is genuine, because the card grants that. It is whether the person it is aimed at has been consulted, and whether you would still want the thing if it turned out ordinary. A story survives an ordinary answer badly. A relationship does not mind one.
Where the card lands in a spread changes what that means. In a position about the past it is often a gesture already made and already answered. In a future position it is more likely a prompt than a prediction. This site treats a reading as a structured way of asking yourself something specific rather than information about what is coming, and this card asks a specific thing well.
Questions people ask about this
What does the Knight of Cups mean upright?
A feeling being acted on. An offer, an approach, a gesture made sincerely and at some cost to the person making it. Romance and idealism are the usual words, and the card does not doubt that either is real.
What does the Knight of Cups mean reversed?
The feeling has become a story with someone else cast in it. Fantasy, inconsistency and jealousy all follow from that single root, which is why the reversal reads more cleanly than most.
Why is the horse walking rather than galloping?
It separates this knight from the other three. The card describes a feeling carried deliberately towards a destination, not a charge, and the slow formal step is how the picture says so.
Does the Knight of Cups mean a romantic partner is coming?
Not on its own. It can describe a person, a gesture, or a way you are currently acting. The question asked and the surrounding cards settle which, and a court card rarely names anyone by itself.
What is its astrological correspondence?
None in the data used here. The card carries water as its element with no sign or planet attached, so the reading comes from the element and from the knight's rank inside the suit.
How does it differ from the Knight of Swords?
Same rank, opposite element. In water the motion is slow and aimed at a person; in air it is fast and aimed at an argument. Both share the knight's habit of going too far in one direction.