We use the phrase 'Whatever happened to xxxx'?' as a kind of rhetorical question, to show regret about something good which has disappeared. It's a rhetorical question because everybody knows the answer - in this case both speakers acknowledge the fact that families nowdays are often too busy to have dinners together. Another example might be if you see a situation where people are being rude - not saying excuse me, thank you or sorry - someone might remark 'Whatever happened to good manners?'

Just a comment, we say 'in this context' but not 'under this context'. What does this sentence mean in this context? Please me tell what this sentence means in this context?