In verse 32 Paul indicates that what he talked about previously was a mystery. So, he knew it might not be clear what he was talking about when going back and forth talking about how a husband should treat his wife.
That's not what "musterion" means. It's not like "a puzzle to be solved". Musterion, translated here "mystery" speaks of something previously unknowable, but now is being revealed. You couldn't know it without God revealing this to you.
Ephesians 5:25-33 KJV
25) Husbands, love your wives, even as Christ also loved the church, and gave himself for it;
26) That he might sanctify and cleanse it with the washing of water by the word,
27) That he might present it to himself a glorious church, not having spot, or wrinkle, or any such thing; but that it should be holy and without blemish.
28) So ought men to love their wives as their own bodies. He that loveth his wife loveth himself.
29) For no man ever yet hated his own flesh; but nourisheth and cherisheth it, even as the Lord the church:
30) For we are members of his body, of his flesh, and of his bones.
31) For this cause shall a man leave his father and mother, and shall be joined unto his wife, and they two shall be one flesh.
32) This is a great mystery: but I speak concerning Christ and the church.
33) Nevertheless let every one of you in particular so love his wife even as himself; and the wife see that she reverence her husband.
The Apostle takes the occassion of teaching concerning husbands and wives to reveal something about Jesus and the church.
Jesus loves and nurtures and cares for the church, so that He can present it to Himself glorious and perfect. This is how men should love their wives.
In fact loving your wife is loving yourself, because just like us with Jesus, the two have become one flesh. This is a mystery speaking of Christ and the church, but is now revealed, we are flesh of His flesh and bone of His bone, being members of His body.
So just like this, the man is to love his wife, because she and he are likewise one flesh. Flesh of my flesh, and bone of my bone.
There isn't actually even a simile of our relationship with Christ being like a husband and wife in this passage. There is a clearly stated identification of of the church being members of His body, of His flesh and of His bone. This is plainly stated and should not be questioned.
The comparison comes in as the Apostle uses our relationship with Christ, members of His body, as the example for husbands and wives, that the husband should love the wife as Christ loves the church. Because just like the church and Christ, the husband and wife are also of the same flesh and bone.
Using this passage to assert that the church is the bride of Christ is misuse, as it does not teach that.
Much love!