This article is a great example of toxic monogamy. Consent has been granted by both parties and the full disclosure will be provided to the pregnancy partner. I don't see how this is strange or unethical at all. If it's hard to understand because of the emotions involved, let me say it takes a ton of emotional maturity to even begin having this conversation before going public with it. We all have our limitations of what we can provide and what we want. Knowing that and encouraging your partner to pursue that, putting ego and heteronormative expectations aside to have this arrangement consensually, makes this healthy.

Wishing them all the best in their journey!