Would the husband be sinful or commit an error by not participating in paying off his wife's debt for an apartment she bought in her name during his imprisonment, despite their return to living together?

The husband is not obligated to pay his wife's personal debts, except for what she borrowed to spend on herself and her children in his absence, in which case the husband is obliged to pay it for her. Providing housing for the wife is not among the expenses obligatory for the husband. Therefore, the husband is not obligated to repay his wife's debt that she borrowed to buy an apartment for herself.