I disagree. I think the ending is actually very realistic and hopeful. Learning to trust someone after trauma takes time, sometimes years. It wouldn't make sense for Jaeha to suddenly agree to imprint just to wrap everything up neatly. That would feel rushed and unrealistic. I like that Jiyoon respects his boundaries and is willing to let trust develop naturally instead of forcing it.

Wow that felt lacking, where's the imprint. The mc haven't even trusted the ml yet and how do you even date someone without trusting the other person. I feel like they'll just break up at some point after the main story, the ending is so abrupt.