It means we should be strict with ourselves in trying not to do any harm to others while generous to others when they do wrong to us, especially if they do so unintentionally.

这句话的意思是, 对自己要严格要求, 不可以做出对不起别人的事情; 对别人要宽容, 特别是当别人对你有无心之失时.

youdao

And so young women often drift "unintentionally" into parenthood with men whom they believe are not good enough to marry or not ready for it.

WSJ: The New Unmarried Moms