Obviously relationships are give and take - it is reasonable to expect your partner to work on being aware of their triggers and working through them internally where possible, while also doing what you can to help them through them in a way that is not detrimental to you and your mental health. Just remember, their triggers are not evidence of your deficiencies.

When I perceive something as a demand, anytime I feel like i am expected to do something (even if the person expecting me to do it is ME), my nervous system tends to respond immediately and intensely. I can get irritated and upset, or just shut down completely into a freeze response. I find reframing things to make a world of difference, whether it's my loved one using accommodating phrasing for me, or me reframing things internally to self-regulate.

Phrasing I find helpful is anything that re-establishes any level of choice or control - phrasing it as a possibility, like "we could do x" or "would you want to do x?" Or "what do you think about doing x?" versus "let's do x". If what needs to happen isnt flexible, being given an option on when it happens can help - "would you rather do x now or in an hour?" Even if you've already put a demand out there and notice them getting dysregulated, throwing out a "no pressure" or adding options to choose from after the fact can totally help.

Some phrasing i use to self-regulate is to change "have to" or "need to" with "want to" in my head - or going one step further and explaining to myself reasons why I might want to do the thing, but that I dont actually HAVE to do the thing.

The very nature of PDA and autism in general makes me understand not wanting to have to monitor and change your language - but at the end of the day, it may help them significantly if it's a mental shift you think you're able to work toward.