Because young boys never put their own selfish interests before what's good for their girlfriend, right?

That dream Finn had. Am I the only one who caught all the subtext or just the first to mention it? if you'll excuse the horrible pun, Finn found Flame Princess kicking Ice King's butt incredibly hot. Toss in some horrible advice from Jake and you've got a melted Ice Kingdom.

So yeah. A horrible thing for Finn to do, but not an unrealistic one.