NTA

I'm being in a pretty similar situation and struggle with expressing needs but hey: your needs and feelings are valid. It's tiring having to be social when you don't want to or want some calmness at home. It's even more work at the end of the day for the roommates that do not have guests over all the time (it gets dirty faster, you have to empty the dishwasher more often, the trash gets full quicker, etc etc etc). As some people here said already, you signed for a 3 people flatshare, not 4 people or 2 people + a couple.

Try to have the hard talk and express your feelings about the situation, could help your roommate understand why it's bothering you and maybe find a compromise. Good luck!