Compenetrados means 'closely united' or 'intertwined', often referring to a deep understanding and connection between people. It's a more sophisticated and less common word than simply 'enamorados' (in love).
In the song, Chayanne uses it to describe the couple's profound bond, going beyond just being in love to a state where they are completely in sync, both physically and emotionally. This word beautifully captures the intimacy and harmony of their relationship.
"Completamente Enamorados" is Chayanne's celebration of a couple lost in the first rush of new love. The night feels endless: the two of them wander the streets together, not wanting to go home, comparing themselves to "two dogs without an owner" because nothing else matters but each other.
As the song builds, the lyrics turn more intimate. Under the moonlight and the shadows of the trees, the couple gives in completely to the moment, laughing, undressing, and losing themselves in each other for the first time. Chayanne repeats the title again and again like a chorus of disbelief: they really are completely in love, and neither one can explain why.
It is a song about that specific, dizzy stage of a relationship when everything still feels new and a little unreal, like being drunk without having had a drink.