Honestly I feel like Louise is mostly at fault here as well. She seems to know how Simon feels for her and has already confirmed her feelings for Ian, so she's just leading him on at this point. Idk if this 'date' has anything to do with the marriage proposal, and she doesn't have to behave coldly to him just because she likes Ian, but it doesn't seem like she's trying to draw any boundaries as of yet. So tbh I feel bad for both Ian and Simon at this point.

Come on Simon I love you are you serious right now... The dude give you everything he treat you so good all we ask is that you don’t go after her I want her to be happy why why do you have to go after her....