I found out my wife (36f) has a bank account that she’s been keeping from me (39m)

I’ve been thinking about this all day and I can’t make sense of it so I’m turning to the Reddit community.

To set the scene, I have been married to my wife for 10 years and we have two boys (6 and 10). I work full time and my wife is a stay at home mum. Our eldest boy is in school and our youngest is at home with her during the day. Financially we do ok, there’s no issues putting food on the table and paying bills, but we’re not going on an overseas holiday every year.

Last night I was looking at our joint bank account on the internet and I noticed an unexpected transfer (about $100 so not huge). I thought this was odd and looked through the transaction history and saw that there’s quite a few transfers to this account – there doesn’t appear to be a pattern to the frequency or amount.

I confronted my wife and she eventually admitted that she has a seperate bank account that she hasn’t told me about. I wasn’t happy about this but what got me real upset was that she refused to show me the account on the internet as I wanted to see how much was in it and what purchases she has made. I called her a liar and untrustworthy which I probably shouldn’t have.

I went to bed without talking to her again. I got up early this morning to go to the gym while she was still asleep which is normal for a Saturday. I went through her wallet and found her bank card. On the way home from the gym I went to an ATM and checked the balance (she uses the same PIN for everything), there was only a few hundred dollars in the account. The ATM only provides the balance and doesn’t show past transactions. This seemed to stack up because I would have noticed money missing from our joint account if she had saved up thousands. She also hasn’t made any unexplained expensive purchases – no new jewellery or expensive clothes. Sometimes there would be something new in the house like a pot plant or a new toy for the boys which I didn’t notice was purchased from our account but I just figured she must have bought it as part of the grocery shop.

What I can’t work out is why she refused to show me the internet banking details. I feel like she’s really trying to hide something but I can’t work out what it could possibly be? And I guess this is my main question to this group. Could it be that she simply prefers to have some independence? Or could it be something more serious?

Thanks everyone in advance for your comments.