The end of Act IV in this play signifies the beginning of the resolution of the problems raised at the beginning of the play. All is restored as it should be, with Titania and Oberon happily together again, Bottom no longer "transformed" with the head of an ass, Demetrius loving Helena and Lysander loving Hermia. However, to treat this play as a simple "love story" or "romance" is to ignore the way that Shakespeare mocks us as humans through his examination of the lovers and how they react to each other.
The point is simply put by Puck in Act III Scene 2: "Lord, what fools these mortals be!" When we are under love's spell, we do stupid, silly things. We do not act rationally. We fail to apply logic to our thoughts and actions. We expose ourselves to ridicule and say and do things that we would never normally say.
Helena adds another dimension to love in one of the most important speeches in the play in Act I scene 1:
Things base and vile, holding no quantity,
Love can transpose to form and dignity.
Love looks not with the eyes but with the mind,
And therefore is wind'd Cupid painted blind.
The magic of love can transform even the ugliest, most stupid of individuals (take Bottom here) and tranform them into demi-gods who we adore and love passionately.
The play ends with a cementing of the relationships by marriage, but the real message of the play is how powerful love is as a force at "beguiling" us and what stupid people we are when we are infatuated. This is something that Puck very cleverly excuses at the end of the play. If you are upset about it, just imagine it is a dream, he says, as he has his laugh at our expense.