Like to a step-dame or a dowager
Long withering out a young man revenue.
Impatient for his wedding night. Comparing the moon to a step mother spending his sons inheritance.
But I will wed thee in another key,
With pomp, with triumph and with revelling.
It turns out that Theseus and Hippolyta are getting hitched because Theseus conquered Hippolyta's people, the Amazons. As we know, the Elizabethans were fascinated by classical myths about Amazons, women who cut or burned off their breasts so they could shoot a bow and arrow more efficiently, raised their daughters to be warriors, dominated their husbands, and treated their sons badly by sending them away, making them do "girlie" housework and/or by killing them.
Why does this matter? Well, because Amazons dominate men, they flip the traditional European gender system on its head. In Shakespeare's play, though, men regain their positions of power over women. (Theseus marries the Amazonian Queen he won in battle and, also, Oberon humiliates Titania and takes away her foster child). At least that's how literary critic Adrian Montrose sees it. He argues that A Midsummer Night's Dream "eventually restores the inverted Amazonian system of gender and nurture to a patriarchal norm."
As she is mine, I may dispose of her:
By him imprinted and within his power
To leave the figure or disfigure it.
Theseus says that fathers are like "gods" and daughters are like globs of wax. (This is a pretty common idea in 16th-century literature, where kids are often said to look like their fathers because they're "imprint[ed]" by their dads' images, much like as humans are said to be made in God's image.) Here, Theseus's metaphor is sinister because he says that, because Egeus had the power to make Hermia in his own image, he also has the "power" to "disfigure" her (body/face) if he feels like it.
You have her father's love, Demetrius;
Let me have Hermia's: do you marry him
The contract has been put together by two men.
What, jealous Oberon! Fairies, skip hence:
I have forsworn his bed and company.