It’s true that she should trust him more. At the same time though, MC apparently went through several fainting spells and had to be hospitalized because she went against the flower.
Her fear of the flower has been fully ingrained into her and Yeonwoo never was able to influence the flower until MC did stuff. It’s understandable that she has a low trust as she knows the harm it causes.
Let's see you go through that and act all ballsy
The plot has to continue with the same characters, just like how OGMC has to be loved by all, she also has to be bullied by the villainess, even if it's a ''powerfull being'' the flower has to keep the core characters alive.
He can physically hurt you sometimes, but it's not gonna work in the long run since people pitying MC will take the attention away from OGMC which is a no-no.
The MC is starting to get on my nerves. She's so afraid of the Flower she became so weak and cowardly??? ''Don't anger the flower it's dangerous!!'' pretty sure he already knows that hun. He stayed here longer than you did and it's obvious he didn't just sit still with his tail between his legs, and he still seems pretty alive to me.