I honestly see no reason why partners request for each other’s password. It’s okay if it’s told willingly or spotted probably when m on my phone but I don’t support it being demanded. Just as you stated.. I take it as distrust when it’s being asked. Because the first question I would ask is WHY?

On the other hand, I strongly believe there’s a level of transparency you’d build with a partner that such things like passwords wouldn’t be placed as too important and that happens in the assurance you have in your partner.

I once had a guy who linked my WhatsApp to his, and even when I found out, I let him read to his satisfaction before ending things up with him on the stand point of not trusting me enough to ask questions and rather choose to invade my privacy and that’s it for me.