Boyfriend (28m) frustrated by how shy I (24f) am about sex and PDA. How can I honor my boundaries while making room for a partner's needs?

I will give a very specific example.

My boyfriend had an apartment room that didn't have an en-suite bath, so his bathroom was right off the living room.

One evening, he and I had sex in his room right before his friends (who I didn't know) showed up. His roommate let them in and they were all hanging out in the living room. He suggested we shower, but I felt uncomfortable with us both going into the bathroom to shower together. We shower together all the time, and I would have loved to do it later that night, but I just felt kind of weird showering together with his friends who I barely knew right outside.

I know this is kind of conservative and awkward of me, but I'm a very private person.

This made him kind of frustrated, and he said my behavior and discomfort was "gross." I apologized, said I would try to get past my discomfort and take a shower with him then, but by that point we didn't have much time and just ended up leaving. He was a little cold but by the end of the night we were over it.

I brought it up again a little while later and told him that I didn't like being shamed for saying no to something that made me uncomfortable. He said he shouldn't have used such harsh language but stands by feeling like my behavior was frustrating and a little hurtful. Even if we shower together on the regular, he didn't like the idea that my inhibitions would get in the way of us having a moment to connect.

There are many tiny examples like this and...I just don't know how to feel. On the one hand, he is allowed to feel how he feels, and I know I can be a little difficult. But also at some point, I want to be able to say no to things without it being a big deal.