Ariadne help to escape Theseus because he need to be free to do something. At the time Theseus was free he go to challenge the Minotour, so if he wins that mean killing the moinotaur, he and all the inocents people could return to Athens and no more inocent have to die a cause of this beast. And he kill the Minotaur with his magic sword.
After Theseus defeat the Minotaur, the 14 young people scape very fast and were happy because they were free forever. Theseus was the hero of all Athens and he made the freedom for all the young people of his kingdom. He was the most helpful person of all Athens.
Finaly Aegeus, Theseus father, saw the boat return but he saw the flag white which means that Theseus was dead because Aegeus told his son that if he was alive he would change the flag to black but Theseua forgot that. So his father was so impulsive thet kill himself for not seeing his son alive.