I think what we see is not Maya feeling fear, but Maya both misreading the situation as well as putting Josy ahead of herself.
She doesn't think Josy feels the same as her about the MC, which couldn't be further from the truth, and shows how Maya isn't perhaps a great reader of people, even someone she's been in a relationship with for a year. Because of this, Maya put what she perceived to be Josy's feelings ahead of her own and that's why she turned him down. However, from this exchange in Ep 5 on that path, it seems she clear she didn't want to do that and she regrets it, and if only her and Josy actually had a proper talk about it, she'd see that she was wrong but then that would just make her feel more regret.