Narration trope that I absolutely despise.
We’ve all seen it done before, the classic trope of a character hearing one side of an occasion and immediately reacting without letting the other person explain. Sure this scene doesn’t have the classic “I can explain” line before the person storms off but it’s still the same trope.
Marian heard Larry was there and lied about being at Delphine’s or wherever and before she confronts him to ask for more info she just breaks off their engagement and avoids him.
Larry lying isn’t a great look but it’s still extreme to just cut it off there without anymore information.