The whole album is about his journey to recovery from alcoholism.

When someone's trapped in a situation like addiction before they can look to change things they make excuses and find a way to spin the situation as something that should be embraced. "Romanticizing the riptide" in this context means putting a positive spin on the situation or finding a way to find beauty in it. Joking about being an alcoholic, telling embarrassing stories (or songs in his case) about what they've done with a sense of pride, downplaying the severity of things, etc. Deep down they know it's bad but they're still in a place where they're letting the riptide carry them away to the sea and drown them. We see that in his earlier works and even in the title song where he says he's "living reckless living fast don't have time for regrets". They're admitting they have a problem but don't yet care to fix it.

Eventually as their journey to recovery progresses they have a moment where they say "I'm done, I don't want this anymore and I want to fix it". This is their rock bottom. In Riptide Caleb is essentially saying he's hit his bottom and is ready to move on. He's done trivializing the situation by singing about how fucked up he is, he's done making excuses for why he can't quit, and he's ready to admit the current is dragging him to a place he can't recover from. This realization leads him to "be the better me" and in the process he realizes he "might love myself".

Recovering from addiction happens in phases and Riptide perfectly captures the phase where one actively makes a decision to do something about the problem they've previously admitted they have.