Tightness?

s

My boyfriend and I were having sex a few nights ago and when he was finally finished I pulled him out and the top half of the condom got stuck in me. Why am I so tight (not that I'm complaining) but even the next day if we try to have sex it takes a while to put it in just because of how tight and tense I feel. At first when he first puts it in it almost feels like a burning sensation until I untense