Descongelando literally means "thawing" or "defrosting," like taking something out of the freezer. It's a creative and unusual word to find in a song.
In "EL AMOR DE SU VIDA," the singer claims he isn't crying. Instead, he poetically describes his tears as "sentimientos que se están descongelando" (feelings that are thawing), painting a powerful picture of long-frozen emotions finally melting and spilling out. This unique metaphor captures the feeling of being overwhelmed by sadness you've tried to suppress.
This song is a perfect anthem for anyone nursing a broken heart with a drink in hand. The singer tries to play it cool, telling everyone, "Si estoy tomando / Es porque estoy echando alcohol a las heridas" (If I'm drinking / It's because I'm putting alcohol on the wounds). He even jokes that he's not crying, it's just his feelings "descongelando" (unfreezing). It's a classic case of trying to hide how much you're hurting.
But then he drops the real reason for his pain, and it's a gut punch. He saw the person he still considers the love of his life, but she was with someone new: "Hoy vi al amor de mi vida / Tan feliz como nunca, besando al amor de su vida" (Today I saw the love of my life / happier than ever, kissing the love of her life). He realizes he's lost for good. The song is brutally honest about the jealousy that comes with a breakup. He admits, "Si les digo que quiero que sea feliz, mentiría" (If I tell you I want her to be happy, I'd be lying), ending with a simple, powerful conclusion: he loves her and envies the new guy.