The Beach Boys – Wouldn't It Be Nice lyrics

The theme of the song is in the title. It starts from a negative (wouldn’t) goes to a positive (nice). The negative of being too young to participate in the niceties of adulthood. A positive in the direction of hopefulness.
The song is sung from the male point-of-view/perspective. The singer is expressing the feelings for both himself and his girlfriend: “the more we talk about it”. Just what is the “it”? The “it” is not lustful teenage s**, nor is it an idealized love. It is a realistic view of the potentiality of a heart-based connection. This couple has spent precious hours discussing their wants, desires, dreams and the ultimate - the purpose of life. They honor each other and feel they can mature into the adult world by being together and supporting each other - “In the kind of world where we belong”. To them they realize that s** and the frequency of s** is not the most important aspect of a relationship. It is more about communication, bonding, sharing, supporting and uplifting each other.
“I wish that every kiss was never ending”. A kiss to the singer is not a euphemism for s**, but symbolic of a forever euphoria that can come from a soul-level connection.
These are two advanced souls/teenagers. They obviously are aware of the pitfalls of teenage marriages, couples deluding themselves thinking that once we get married everything will be perfect. That is not the case here, they are willing to wait. And it has nothing to do with religion, the devil or promises made to parents or some deity. It is their profound awareness of the riches that life has to offer - if it is approached properly. “Oh, we could be married and then we’d be happy”. That line is sung in a flippant/playful manner. They would be happy married or not. That is not their goal. They are not wanting a marriage to escape loneliness, neediness, but of blissful togetherness. A nurtured, lasting relationship is foremost. Together the two of them can forge/build the kind of world where they belong and there wouldn’t be a single thing they both couldn’t do.