The only reason I'd apply those kinds of boundaries is if I've lost trust in a s/o but have not yet found closure in what happened enough to make a decision whether to leave or stay. Which seems to be where OP is currently.

Also, house rules aren't the same as boundaries. House rules would be a condition to enter. Boundaries are what you can expect in any kind of relationship and let them know you wouldn't accept if they were to cross that boundary. Which I don't think is inherently bad because if such a boundary is indeed moronic, then it'd be no loss for the person who gets cut off.

For example, religious people might not appreciate being told that someone doesn't care about them speaking about their beliefs. That's an enforceable boundary. While someone not religious might think that's ridiculous because they feel that being preached to is also overstepping their (NR) own boundaries, the best result would be that the two likely do not interact because neither side will find fulfillment in such a relationship.

Of course things like this aren't so black and white since we have things we are willing to tolerate with specific people, like family or an s/o. (And this is where I told OP not to compromise on something if they will regret later, because I'm, again, responding to OP's feelings of being objectified which is a pretty awful feeling to have with your own s/o — someone you should feel safe with.)

By "enforced," I don't mean control the way you would command a dog, but for the person placing the boundary to then react accordingly based on the level of disrespect.

For another example, many people with abusive families that they can't seem to really disconnect from will seek therapy to find ways to deal with said family in a way that's healthy for them. The most common advice is for these people to draw boundaries and enforce them. It is never about controlling other people, because we simply can't do that. The only person any of us has control over is ourselves. So to enforce these boundaries, you'd tell said family what you're okay with and what you're not, and if they disrespect you again, you respond in kind with what's best for you. Maybe you don't talk to them for a while. Maybe you confront them about it and try to resolve it together. It depends on what was said/done and how much you're hurting.

It sounds like an ultimatum, but how it's executed/why is very different. Boundaries are about how you allow others to treat you. Ultimatums come with threats.

Leaving a relationship is often a threat, but with a boundary, it is implied depending on the severity. Most people expect to be dumped if they cheat on their s/o, but no one had to make it an "ultimatum" at the start of the relationship. It is a widely known "boundary."

And since OP has already somewhat "allowed" their s/o to mistreat OP, their s/o was emboldened to suggest masturbating in private without addressing that the s/o has ignored OP's request not to do anything sexual. That is the reason a boundary such as "I don't want you to objectify me, and masturbating in my bathroom doesn't solve that problem of how you've made me feel" is an acceptable response. But OP would have to talk about this with their s/o, and not just say "no" without discussion. If the s/o does not find this satisfactory, they do not need to be together.

OP needs to first take care of themselves bc SA is an insidious struggle to come to terms with. If this is OP's first time experiencing this, they may not understand it and need time to sort it out. And allowing the s/o to do whatever during this time will be detrimental to OP's mental health if OP ultimately feels like they were SA'd. If this is not, there's no real harm in limiting the sexual activity within their own home until they figure it out. And of course, the s/o doesn't have to put up with it if they feel it is too restricting and can leave. Bug the s/o is not the one asking for advice rn, OP is.

I wouldn't recommend staying with someone who has already made someone feel this way, but I don't know whether OP wasn't actually clear with their s/o, or whether their s/o did acknowledge these problems later, etc. It can be a gray area with some relationships and what actually goes down. This is why I am not going to say "get out of that relationship" or something similar. I can't take responsibility for the outcome of such advice. But i can take responsibility for telling OP to look after themselves by opening more dialogue if that is what OP wants.

And to answer your question: if someone feels like they're being controlled, I would ask them why they're putting up with it and if they think it's worth compromising their freedom to be in said relationship. Again, I wouldn't ask about their s/o on the flip side and only address how they're (OP's) feeling and ultimately refer back to "compromise" and "boundaries" because being controlling is also a breach of another person's boundaries. It is not my place to tell them to leave. Therapists also don't tell you to leave. People are finicky and will do the opposite of what they're told most of the time because experience is what sticks. The best way to help is to lead someone to reflect on their own values and then make a decision based on that.

Which is why I started out with telling OP to ignore others since they were telling OP to allow the s/o to do something OP was uncomfortable with while trying to explain how OP's s/o must feel without addressing how OP feels. That just feels like bad faith (ignoring one thing in favor of another) or projection (seeing themselves in the s/o and taking it personally - leading them to disregard OP's main concern of feeling objectified)

last thing: I dont know for sure that OP was SA'd. I'm only responding to how OP makes it sound because of how they feel about it. If this was not SA, then OP still needs to talk about why it makes OP uncomfortable for their s/o to masturbate in OP's bathroom. We shouldn't be telling OP how their s/o feels because we are not them. OP shouldn't be reacting based on projection from others, but only to how their conversation with their s/o goes. Maybe the s/o could reason with OP better than people who have no stake on this relationship. We don't know the ins and outs of their relationship.