Blame it on the old English people…
louse/lice — lus/lys
mouse/mice — mus/mys
house/houses — hus/husian
Note how the old english has the “-ys” ending for “-ice” in modern English. This is called the i-mutation. The ‘u’ in the singular (‘ou’ in modern) is a pronounced as ‘oo’ (same as in Latin).
Now notice that the plural of house has an “-ian” ending in old English. This is a different plural ending similar to man/men and ox/oxen. In fact, the plural of house used to be housen (still is in German–hausen). It turns out that house is a neuter noun and mouse and louse are feminine nouns which is why they’re pluralized differently.
PS- Mouses and louses are acceptable pluralizations in modern English.
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