It sounds more like a reevaluation of your partnership is in order if you two are disagreeing on a core value.

You're using a lot of strong, passionate language to convey how you feel: "criteria", "high intensity", "significant amount of alone time", "extremely...fearful", "tokophobic", "crippling low pain tolerance", "all the effort that is required to get there"...

Do you really want this?

Not once do I see a mention of how you envision your life to be enriched and fulfilled by taking this path. That's worth noting.

The reality is pregnancy is a very significant, very serious physical and mental undertaking. People can have lasting physical complications from this process. People can have lasting mental complications from this process. People die. Is that a risk you're willing to take? I am not trying to make you uncomfortable but this is a very real truth and not enough people weight the dynamics of this undertaking. You do not control whether you have multiples. You do not control genetics. You do not control whether you endure medical situations that may accompany being pregnant.

Pregnancy is an enormous test in letting go of control.

If your partner truly wants to concieve and you truly don't, you two need to sit down and have some very honest conversations about the journey you two have embarked upon and whether the fork in the road is one you travel together or each separately on your own.