Ending?

The point is not so much whether or not she gets with Jaakko. The important development is that she resolves not to go home to Céline (she walks away from the flight to Paris and leaves her souvenir behind).

Jaakko has a complicated life with compromises and disappointments, but he has chosen his path. Caroline was uncertain; she is in a relationship but can only maintain it with a lot of lying and self-disgust, and she clearly isn't getting (or giving) the fulfillment that relationships are supposed to be about.

Making the decision not to continue is the big development of the movie. Every turn and twist before that was merely a reveal to the viewer of something that was already the case. Now things have actually changed. Caroline can go on alone, or she might follow Jaakko, or meet someone else fulfilling. Given that they seem to have had a genuine connection, Jaakko might be the more likely option, but the script doesn't say.