Dark Harbor - what about the watches?

hallo folks, I've just re-watched Dark Harbor yesterday night and there's this scene shortly before the climax, when Alexis checks the time on David's watch. David seems kind of pissed of of even alarmed that she isn't wearing her own watch because she usually always wears it. Did u understand why she isn't wearing it of why this seemed to be a problem for David?
And shortly afterwards the unnamed young man says he likes David's watch. There has to be a special meaning behind this statement, hasn't it? Can u help me there?