Short answer: Janie's need for love involves genuine passion and love, as well as a sense of equality and friendship. With these she is satisfied; without all of them, Janie is not happy and seeks more in her life.
Early in the novel Their Eyes Were Watching God, when Janie's grandmother discovers her granddaughter kissing "shiftless" Johnny Taylor across the gatepost, she becomes alarmed although Janie tells Nanny that she has meant no harm. Her grandmother replies,
"Dat's what makes me skeered....You don't even know where harm is at....Ah can't be always guidin' yo' feet from harm and danger. Ah wants to see you married right away."
Knowing how pretty and innocent Janie is, her grandmother marries her off to Logan Killicks, a man who is much older, but who will keep Janie "safe," she hopes. As she holds Janie, Nanny tells her the tragic story of her mother that she does not wish repeated with Janie. But, after six months Logan starts to treat her with less amazement about her beautiful hair; instead, he expects her to work like a farmhand. So, when Joe Starks, "a cityfied, stylish-dressed man with his hat set at an angle that didn't belong in these parts" comes down the road one day, Janie is curious about him. He tells her that he is on his way to a town run by black folks and he wants to invest in it before it is too late. But, taken with Janie, he stays for a week or two until he convinces her to come with him where the future is bright. Janie decides the change will do her good. She meets Joe at the road when he approaches with a rig. As they head toward Florida, Jane muses,
From now on until death she was going to have flower dust and springtime sprinkled over everything.
Unfortunately, "springtime" does not last because Joe treats her more like property. He has her work in his store and does not allow her to show her beautiful hair, having ordered her to cover it. She cannot laugh and talk to the men on the porch of the store as he does; in short, she is his special property. This role grows old for Janie, who notices, too, that Joe is aging. One day Janie makes an error in the store and Joe insults her before all the customers. When she retaliates later at home against his insult by saying something personal about his aging maleness, Joe makes a strange sound in his throat and dies.
After Joe's death, Janie is still not free because she has a position in the town to maintain; furthermore, she is not satisfied despite being wealthy and having men wish to marry her. Janie feels that she "had been getting ready for her great journey to the horizons in search of people." She has no interest in worrying about things or possessions. Janie also promises herself that she will no longer be "whipped."
One day while the townspeople are at a baseball game, a handsome man comes to the store. He tells her he thought the game was at another park and chats with Janie; then, they play a game of checkers, a game Janie was forbidden to join in on at the store when Joe was alive. When it grows late and Janie closes the store, Tea Cake, whose real name is Vergible Woods, walks her home. Janie feels as though she has known Tea Cake "all her life." This is a man with whom she can be an equal; she finds in Tea Cake what she has yearned for with Joe: mutual affection and respect.
Freed now from Joe's binding obligations and mental anguish, Janie regains her youthful joy in living, even her innocence, with Tea Cake. Later, she decides to marry Tea Cake because she can be herself with him. Tea Cake loves her very much, telling her,“nobody else on earth kin hold uh candle to yuh, baby. You got de keys to de kingdom.” Unlike Janie's other husbands, Tea Cake treats her like an equal, a friend as well as a lover. They work side-by-side in the muck in Florida, they laugh together, play together, and love together as equals. For Janie this is the meaning of love and the satisfaction that this great emotion gives her.