Partner's health issues affecting relationship.

[Nuke]

She has endometriosis. Causes abnormal pain during menstruation. Had multiple surgeries during her life and it just returns after a while.

Endometriosis is most likely caused by a hormone imbalance, basically boils down too much estrogen and too little progesterone. That is why it will keep returning. Endometriosis itself, and its hormonal origin, may both cause some of the problems.
Has she tried high doses bio-identical progesterone? On the one end it will balance the estrogen, but it act as a precursor to many steroidal hormones and it will also have a calming effect in the brain by converting to allopregnanolone.

https://naturone.com/sa-products/ This is the one me and people I help out uses.

I'm not a doctor, but have quite a bit of experience with steroidal hormones. Ironically more with the female hormone system than with the male.

 

[C4Cat]

Endometriosis is most likely caused by a hormone imbalance, basically boils down too much estrogen and too little progesterone. That is why it will keep returning. Endometriosis itself, and its hormonal origin, may both cause some of the problems.

Actually the causes of endometriosis are still unknown, a hormone imbalance is not one of the current theories for it's cause. It certainly doesn't simply 'boil down too much estrogen and too little progesterone'.
Progesterone is, however, sometimes used to treat endometriosis but it doesn't always work and comes with many, often serious, side effects. I personally wouldn't just order products online without discussing it first with a specialist doctor.