If your landlord breaks into your apartment or enters it without notifying you, this is grounds to break a lease. You can't break a lease just because there was a break in, however. Landlords are not...
I guess there isn't much of a difference. A break-up is a full-on split, and a break is a chance to be apart, for your partner to see wether he likes being apart from you, or wether they should carry...