Mice, lice, rice, blouses, houses, spouses, ice

Why is this?

Some grammar rules are easy to explain to my 5-year-old.

Some are not.

This one is not:

Mouse x 2 = mice

Louse x 2 = lice

Blouse x 2 = blouses

House x 2 = houses

Spouse x 2 = spouses

ice/ice = ice

rice/rice = rice

Why? Is it because typically there is never a single ice/ouse?

Or that most commonly people aren't afflicted with a multitude of hice or spice, but have just one?

Is the "ice" plural used only for the animate? Because my spouse = totally animate.

If you double-douse someone, you usually haven't diced them. At least not simultaneously.

Humph!