Ventura can mean 'adventure', but in the context of relationships, it often refers to a 'fling' or a casual affair. It's a more nuanced word than just 'adventure'.
In this song, the singer uses ventura to describe a past relationship as "una ventura, un capricho pasajero" (a fling, a passing whim). This highlights the temporary and superficial nature of the relationship, contrasting it with true love and making it an interesting word choice for learners.
Abraham Vazquez's "Tan Poco" is a really honest look at a relationship where one person feels like they gave everything, and the other gave, well, "tan poco" [so little]. He's tired of the constant complaining, even though he put in all his time and effort. He even says, "prefiero quedarme solo a que me la gaste" [I'd rather be alone than waste it], showing he's reached his breaking point.
He thought this person was changing, but he was wrong. He calls the relationship a "ventura, un capricho pasajero" [an adventure, a passing whim], and now he's ready for a new adventure himself. It's clear he's hurting, drinking "para no pensar que tú estás besándote con alguien más" [to not think that you are kissing someone else]. He's decided that being alone is better than getting so little in return.