Sex is a lot like Legos.
. . . Okay, cut me some slack. As the mom of three boys, there seem to be Legos everywhere I look! Still, I think it's a good analogy.
The first time a child sees a box of Legos, he might be naïve enough to think that the box actually contains a toy that looks like the cool picture on the front. Imagine his disappointment when he opens the Lego box to find hundreds of seemingly random pieces of plastic instead of the Batmobile or starship that was promised by the box cover.
The genius and fun of Legos is creativity. First, you follow the directions and build the design represented on the box. But then no child can resist the desire to build something new—to tear the blocks apart and start another creation.
Back to sex. The world may have painted for you a picture on the box: a blissful experience of exquisite pleasure and oneness. Perhaps you have been surprised and disappointed to find that sex has created more conflict in your marriage than intimacy, more pain than pleasure. The metaphoric "pieces" of this gift seem to be strewn around your bedroom, bearing no semblance to the gift you expected.
Every marriage experiences some obstacle in physical intimacy: differences in desire, medical issues, recovery from sexual abuse, baggage from poor choices in the past, involvement with porn, or a poor body image, to name just a few. I'm sure you've had times in your marriage, as I have, when you ask God, "Wasn't this supposed to be a gift? With all due respect, God, I think the gift is broken. Any chance I can exchange it for something else?"