Why is this the answer?

The answer is kiss because this clever riddle uses fun word pictures to describe something that shows love, affection, and happiness. It is a special secret code about the simple action of a kiss. Let us look at the first line: "Of no use to one." This is a super clear clue! Can you give a kiss to just yourself? If you try to kiss your own hand or arm, it is not the same as giving a kiss to someone else. A real kiss always needs two people. It is something you share with a friend, a family member, or a sweet pet, so it is "of no use to one" person all alone. Next, the riddle says, "Bliss to two." Bliss is a wonderful word that means perfect happiness. Think about the feeling you get when you give a kiss to your mom, dad, or a grandparent. It is a sign of love, and it makes both of you feel warm and happy inside. That shared, great feeling of joy between two people is what the riddle calls "bliss to two." It is an instant feeling of affection. The third line is tricky. It says, "Men lie for it." The riddle is talking about how very important a kiss is, especially in grown up stories, like fairy tales or classic movies. Sometimes people in these stories want a kiss so badly that they might pretend to be someone they are not, or they might act silly to try and get one. The phrase just means that a kiss is considered a highly valued thing, like a great treasure, that people sometimes try too hard to achieve. Finally, the riddle ends with, "The baby’s right." This clue is pointing to the simple, pure way that babies often show affection. If you watch a little baby, they often make a funny, loud sound—a little smooching noise—with their lips. They are learning how to show love, and the riddle tells us that the baby’s instinct to make that sweet sound is exactly right. The answer kiss is the only thing that fits all these playful and sweet clues about sharing happiness and affection.