**Resign** - accept that something undesirable cannot be avoided.

*Dad resigned to his seat. "Fine," he says.*

**Relent** - cease resistance.

*Dad sits back in his seat. "Fine," he relents.*

**Capitulate** - cease to resist an opponent or an unwelcome demand.

*Dad sits back in his seat, capitulated. "Fine," he says.*

**Acquiesce** - 
accept something reluctantly but without protest.

*Dad sits back in his seat.  "Fine," he acquiesces.*