The Conundrum of Mutuality of Consent: Section 21 of Hindu Marriage Act

I'm reading through Hindu Marriage Act and I'm getting my head around Section 21, but it's driving me crazy. So, if the husband and wife are unable to agree on the matrimonial home, the husband can claim it as his exclusive possession under Section 19, but only if he's been living there for a period of 1 year prior to the separation and has given his wife a 3-month notice (Section 19). But then, Section 21 comes in and states that even if the couple has agreed on the matrimonial home, if they've been living separately for a period of 1 year or more without any resumption of cohabitation, the matrimonial home becomes the sole property of the husband. Isn't it that the couple's agreement takes priority over mutual consent for the home?