What do you think about Olaf saying "I guess Kristoff doesn't love you enough to leave you behind"? Is it a hint to the audience that maybe Kristoff is not the true love Anna's looking for? I thought it was a joke, but the more I watch it, the more I think it has a deeper meaning than that.
It has a literal meaning. Kristoff takes Anna back to the castle because he loves her and if you love it, let it go (not as Elsa did). This is one of the many acts of true love the other characters start to do for Anna but they don't save her because the act of true love has to be done by her.
You have to remember that when Olaf says that line he's explaining what true love is to Anna. "Love is putting someone else's needs before yours like, you know, how Kristoff brought you here to Hans and left you forever" and then he says "I guess Kristoff doesn't love you enough to leave you behind"
It does have a deeper meaning though. The movie makes the audience think that Anna will be saved by the all romantic true love's kiss. This starts back with the trolls who when Great Pabbie tells Anna she needs an act of true love they immediately suggest a kiss.
At the end, it is Anna's sacrifice of love for her sister that saves her. It's not romantic love but platonic and sisterly love.