relent

verb [vi. 不及物动词]变宽容，变温和；终于同意，不再反对；（天气）转晴，缓和，转好；<旧>使变温和，减轻

Finally his mother relented and gave permission for her youngest son to marry.
他的母亲终于发慈悲，允许她最小的儿子结婚。