此后 indicates the result of an action or event.
此后 can serve as a conjunctive adverb and be placed either at the beginning of a sentence or in the middle of a sentence.
It can also serve as an attribute.
此后 in the middle of a sentence
If it is placed in the middle of a sentence, it means "thereafter".
These sentences consist of the following two parts:
1) the first clause expresses an action or event;
2) the second clause, beginning with 此后, expresses the result of the action.
In this case, we should put a comma before 此后.
We haven't spoken to each other since we fought two months ago
wǒmen liǎng ge yuè zhīqián chǎojià le, cǐhòu zài yě méi liánxìguò
She hasn’t left her house since her health took a turn for the worse
tā de jiànkāng zhuàngkuàng jíjù shuāituì, cǐhòu tā zài wèi líkāiguò jiā
此后 at the beginning of a sentence
In sentences with 此后, the starting point can be omitted. It can be clear from the context.
In this case, 此后 is placed at the beginning of a sentence and has the meaning “after this”, “after that”.
In this case, we often put a comma after 此后.
After that, you'd better not come here
cǐhòu, nǐ jiù zuì hǎo bù lái
Things started to get out of hand after that
cǐhòu shìqíng kāishǐ shīqù kòngzhì
此后 as an attribute
此后 can also serve as an attribute and have the meaning "henceforth", "hereafter". In this case, the particle 的 is usually placed between 此后 and a noun.
They laid the groundwork for future development
tāmen wèi cǐhòu de fǎ zhǎn diàndìng le jīchǔ
In the months that followed, I saw most of her family
zài cǐhòu de jǐ ge yuè zhōng, wǒ jiàndào le tā dàbùfèn jiārén