Shakespeare did an excellent job in A Midsummer Night's Dream of showing us different types of couples and different types of relationships. While the fairies serve many functions all throughout the play, one of the functions Oberon and Titania serve is to represent an older, married couple that has become disenchanted with their relationship but makes amends at the end.
Oberon's and Titania's dissatisfaction with their marriage is portrayed through their external conflict of both wanting to care for the changeling Indian boy. Titania has created a rift in their marriage by caring for the boy above Oberon, and Oberon has equally created a rift by becoming jealous of the boy.
Literary critic Shirley Nelson Garner points out that Titania's affection for the boy can actually be seen as a bit erotic. Puck describes Titania as crowning the boy with flowers and making "him all her joy" (II.i.27). We know that for Titania this describes erotic love because she is described as treating Bottom in the exact same way when she falls in love with him, as we see Oberon describe in his lines, "[S]he his hairy temples then had rounded / With coronet of fresh and fragrant flowers" (IV.i.50-51). Hence, since Titania's affection for the Indian boy is clearly erotic, Oberon has a right to be jealous, wanting all her affection to himself. Thus, Oberon tricks her into giving up the boy by making her fall in love with a much more hideous and ridiculous creature.
When Oberon releases her from the spell, he commands her to be "as thou wast wont to be; See as thou was wont to see," which apparently makes her see Oberon as her love again, instead of the Indian boy (70-71). Since Titania fully releases her affection for the boy, there conflict is resolved, showing us how Oberon and Titania serve the role of represent an older couple with problems in their relationship that they resolve in the end.