Cats are said to be independent, aloof, and not in need of company except on their terms. This is true only of some cats; certainly not all. Cats raised by people from an early age either think they are almost human, or that the human is almost a cat.
In fact, throughout a cat-person bond, the two may switch roles without realizing it. On occasion, a cat will bring home a dead or half-dead animal as a token of her love and respect (a touching, if gruesome, method of confirming the bond).
Bringing home "love offerings" of this type is a sign of attachment and belonging. There are others that require less clean up.
When the bond is strong, a cat will:
Tend to follow you around. She may not follow immediately, but after a moment or two she might casually saunter into the room where you're sitting (as if she's trying to play the whole thing down). Your cat may jump in your lap or may just find a chair nearby. Either way, she prefers to spend time with you.
Become slightly depressed when you leave, and greet you enthusiastically upon your return. She may learn to recognize the sound of your car pulling up and run to the door, expecting your presence.
Send subtle cat signals of affection to you throughout the day. These often take the form of classic "cat kisses" – staring at you adoringly, then squinting or slowly closing her eyes.
Send not-so-subtle signals, such as rubbing her head upon you (marking you with her scent), and of course, purring.
Lying on her back, with her stomach exposed. This is a sign of trust, because your cat is now in a vulnerable position. Many owners mistakenly think this is a request for a belly rub. It usually isn't.
This is a cat's affection at its most intense. They can't hold your hand, and they are not given to jumping up and kissing you. There's no difficulty to describe this sort of relationship as love.