I’m in the exact same boat. I’ve always preferred “partner” over “girlfriend” / “boyfriend” since I think it’s a better description, because they are my life partner. I also use it because if I’m talking to random strangers (like on the internet), they don’t need to know my situation. I also like it because it hopefully makes the term more widespread / removes some of the stigma, since maybe people won’t assume the person is LGBTQ (or just won’t care) given I’m cis+straight.

But I too will be switching to “wife” tomorrow