Desemboca literally means 'flows into' or 'empties into', often used for rivers. It's a more evocative and less common word than simply 'leads to' or 'ends up'.
In this song, Tommy Torres uses it metaphorically to express how all his thoughts and ideas inevitably lead back to the person he's obsessed with. He sings, "Toda idea desemboca en ti" (Every idea flows into you), painting a vivid picture of his mind's constant return to her, like a river to the sea.
Tommy Torres opens this one almost apologetically, like he's confessing something he still can't believe happened. What began as flirting, just looking a little too long at someone's mouth, turned into something he never signed up for: "Se me salió de las manos" (It got out of hand). By the time he admits that, he's already past the point of no return.
The chorus is the whole song in one line: "Todo me recuerda a ti" (Everything reminds me of you). He can't write a single verse without it landing on her name, "Y no hay verso que me salga / Que no rime con tu nombre" (And no verse comes to me that doesn't rhyme with your name), which is either the most romantic or the most exhausted a songwriter can sound. He skips mornings, avoids the street, and lies awake picturing her at night. There's no bridge that resolves any of it. He's just stuck, and honest enough to admit it.