Man and woman were created in a way that leaves them with only two options: They can either help each other or oppose each other. In fact, man and woman are opposites, and ought not to be able to connect. However, God makes peace between these two opposites and enables them to become connected to each other.

If he merits, she is a helper; if not, she opposes him:

[In Genesis 2:24, God refers to woman as] “ezer kenegdo (literally, a helper opposite him).” [The Talmud, building on the seeming contradiction between “helper” and “opposite him,” states: “If he merits, she is a helper; if not, she opposes him” (Yevamot 63a)]. The explanation is that this help [of a husband and wife] is different from that of a father to a son or vice versa, for a father and son never truly oppose each other. In contrast, this helper [the wife] is “a helper opposite him (kenegdo).” The woman is equal to and as important as the man. She helps him, for the man brings [raw materials like grain or fabric] and she develops it [by making bread or clothing]. This is referred to as “a helper opposite him.” However, if he does not merit, she is totally against him, whereas a father is never totally against a son. This seems to be the simple understanding of this passage…

Only God can connect two opposites like a man and woman:

There is a very lofty concept here, for male and female are two opposites, he a male and she a female. If he merits, they combine to make one totally united power. For each pair of opposites unites into one power when they merit. God, may He be blessed, makes peace between these opposites and connects and combines them… Therefore, when they do not merit, the fact that they are opposites causes them to be opposed to each other, for there is no combination and connection from Above. (Maharal, Ĥiddushei Aggadot, Sota 17a)

Further reading: For more about the wedding, see p. 16; A Concise Guide to Halakha, p. 47.