would you consider allowing your partner to have a sexual relationship elsewhere? If not, why not... why would you think it right to force your partner into celibacy?
You are presenting two options:
- an open relationship
- celibacy
when in fact the partner has a third option which is to leave the relationship and be single.
But a relationship is not 90% sex and 10% everything else.
People place such importance on sex until they have to chose and then suddenly they start to appreciate the love, company, trust, family, comfort, security, fun, familiarity, care, support, affection and bonding that is all there in a relationship.
Anyone who would give all that up just for the chance of being single and finding someone to have sex with cannot be as invested in the relationship as they think they are imo.
OP would do better to accept his wife and her medical problems. Cherish her the way she is and be grateful for all that they have together. Yes, help and encourage her to find medical solutions but also realise that if it's not possible, her right to not suffer pain for the sake of sex is more important than his urge to ejaculate.
If he could do that and she wasn't afraid of having to constantly reject his advances then the intimacy could start to grow again in their relationship. He should let her lead this. All this pushing is just pushing her away and, yes, it could end the relationship.