I have so many thoughts. Before I forget, @JeNeBaguetteRien, you have an awesome username. I have seen you around before and keep forgetting to mention it.
Onto business. I personally think that the shower, the pizza, and the lock on the door are ALL red herrings. The crux of this scenarios runs thusly:
OP: Please do not do the thing.
DP: But whyyyyy
OP: Because I don't like it.
DP: Fiiiiiine.
DP: ~passive aggressively tests the very edges of this new boundary~
- If OP says "please don't do the thing", it doesn't matter WHAT "the thing" happens to be, her DP needs to just shut his mouth and stop doing the thing. She shouldn't have to explain herself, or justify her reasons. Asking should be enough.
I had a friend who did a similar boundary stomping dance every time I made a reasonable request. I would say "please don't do the thing" and would be immediately subjected to half an hour's lecture on why the thing isn't a big deal and I was unreasonable for asking that it not be done to/around me.
Different people have different likes and dislikes. Boundaries still matter.
OP has the right to set a boundary without having to enter into conversation about it.
- The man is behaving like a toddler. He is an adult. He knew three things:
* That OP was in the shower (or he wouldn't have stood out there knocking)
* That OP did not want him to come in (or he would have just gone straight in)
* That the pizza would be ready in ten minutes (or how else could he have said that when she opened the door?)
Based on those facts, those pieces of knowledge that via deductive reasoning we KNOW he was in possession of, there is no reason why he could not have
* Waited until the OP was out of the shower to put the pizza on
* Eaten without OP, if she wasn't out in time, and saved her some slices that could have been eaten cold, or reheated if that was OP's preference. (And cold pizza is pretty great anyway.)
Instead of taking either of those two options, which most reasonable, thinking adults would have done, he
chose to put the pizza in the oven when he
knew OP was in the shower, when he
knew she had asked him not to come in... so that he would have a reason to bang on the door and play the wounded victim "Oh, but I made you lunch, I was just trying to do something nice" card when she (rightfully) got peeved off with the passive aggression.
And too many of you are giving him a pass to behave this way.
So. Bottom line. He knew exactly what she was asking, and he first a) argued the toss, as if OP's wants/needs surrounding her own body are up for discussion (protip: they're not), and then b) orchestrated a situation where he could push that boundary as far as possible while still maintaining the option of playing wounded victim when OP got upset.
But go ahead and tell OP that she's being unreasonable. Tell her that just because she consented to sex with this man, that now means she has no right to set any boundaries with him at all, ever again. Tell her she's "hard work" because she wanted fifteen uninterrupted minutes to herself and her DP not only couldn't even give her that, he manufactured a situation to deliberately interrupt and make out like she's the unreasonable one.
All I know is, people who can't respect my simple boundaries and requests don't violate my bigger ones - because I fade them out/cut them off before they ever get a chance. If you can't listen to a "no" in a simple, low stakes situation like this, you get me thinking about what other situations you're going to ignore my "no" in. A simple google search will turn up countless stories of women/people who ignored red flags like this.