I definitely agree about Henry waking Maria to different possibilities in this chapter, and that this little exchange is when she starts to seriously want him instead of just having fun flirting with him. But I don't see him as the bother. Julia's the one who keeps bringing up her engagement to Mr. Rushworth and their impending marriage; Julia's the one who talks about it so much and so loudly as to catch Mr. Rushworth's attention and "expose her sister to the whispered gallantries of her lover..." and when they leave the chapel, Julia's the one Maria is unhappy with.