Aries: 48 hours maybe?

Taurus:Until they die. Maybe not even until then.

Gemini: Give it 35 seconds (big oof)

Cancer: Years

Leo: Until the end of time

Virgo: Couple of months

Libra: 0.2 seconds unless you really messed up

Scorpio: all eternity

Sagittarius: Two days

Capricorn: Don't even bother apologizing

Aquarius: A year

Pisces: 2 months maybe? (for me it really depends what the grudge is)