We've always had joint accounts. We've had many years with one income source. I was a SAHM when our boys were younger and 5+ years ago I quit working so I could travel with my husband (joint decision and neither of us regret). Married 39 years this fall.
I know one couple that had separate accounts - found out after they divorced. The husband had his own business. They also had a house rental - all of that money went into his account. He had access to her account and, as far as I know, she was not allowed on his business or personal account. Majority of the bills were paid through her account and often he refused to contribute. Since he had access to her account, he would sometimes pay a bill early, do it right before she was going shopping (sometimes grocery shopping), make it so she didn't have enough funds and had to dip into her personal savings.
I know one couple that had separate accounts - found out after they divorced. The husband had his own business. They also had a house rental - all of that money went into his account. He had access to her account and, as far as I know, she was not allowed on his business or personal account. Majority of the bills were paid through her account and often he refused to contribute. Since he had access to her account, he would sometimes pay a bill early, do it right before she was going shopping (sometimes grocery shopping), make it so she didn't have enough funds and had to dip into her personal savings.