Control and manipulation could become a common theme between you two during the next few years, potentially making your relationship a battleground if you don't both take measures to avoid that outcome. What's happening now is that you're both being pushed into an uncomfortable corner, communication-wise. Old behaviors that you may have thought you'd tamed come to the forefront now, as if you're each regressing back to your childhood or teenage self -- being sarcastic with each other, always needing to have the last word or prove your sweetie wrong, even when they're right.
Needless to say, treating each other like this will start plenty of arguments, and since neither of you is in prime communicative form now, they'll most likely devolve fast into out-and-out fights and hurt feelings all around. There is a better way, though. Try to catch yourselves when you're behaving in a petty way, and as difficult as it may be, take the higher road. Apologize when you treat your sweetie disrespectfully, even if you think they're being too sensitive. A few niceties like this will really help you get through a troublesome few years.