sex still hurts

i’ve been having sex for almost two years. it’s not regularly. maybe once a month or at most 2-3 a month.

I’ve been with the same partner as well so i’m completely comfortable.

It always hurts pretty bad when he first puts it in and then throughout it feels a little painful and uncomfortable. It’s only felt like good once or twice.

Is it because we don’t do it regularly and my body is still adjusting?