Chewing gum equates with the pleasure of food? Maybe if Willy Wonka made it.
A closer analogy (especially if we’re talking about contraception between a couple who aren’t married) would actually be something like going to a buffet, taking several full plates of food, chewing it up and then spitting it out without swallowing, all before leaving the buffet without paying.
Food is not to be misused in that way, and all the more a human being should not be misused. We should take as much food as we need, and we should use it for its nutritional value and for its sustenance. We shouldn’t simply chew it, enjoy its taste, and then spit it out while wasting massive quantities of it.
The fullness of the digestive system cannot be properly realized without properly using food. Likewise, the fullness of marriage cannot be realized without properly engaging in sex. But unlike the digestive system and food, marriage is not intended for everyone, and neither is sex. We admit this to some extent, such as in the case of children. But we don’t admit this as completely as we ought to.