I found this sentence in From Memories by Sarah White. Is it correct? I think the tense is a bit strange here.
She looked sad like after you have your loved one pass away.
There is nothing wrong with the sentence grammatically (except that it would be clearer if there were a comma after sad), but it is written in a very colloquial register, and it employs have in a way you may not be familiar with.
The colloquial part is the use of like where formal English would employ as. The like phrase compares the woman’s sadness to what you, the reader, might feel after a particular sort of experience. The experience, the object of after, may be expressed as a noun, as a gerund clause, or as a finite-verb clause
Here are examples of the construction with a noun and a gerund phrase (they're from the first page of a Google search on "sad like after"):
... feeling sad—like after a lousy day at the office or a fight with someone you love
It's a good sad, like after watching a really tragic movie and you've just cried your eyes out while eating an entire box of chocolates
Here are examples with a finite verb in the past tense.
He was still sad—like after you left I feel sad (like after we lost the girls)
Those two have the verb in the past tense because sad is compared to the feeling prompted by a specific past event. But the verb can also be cast in the present tense if you compare sad to a ‘generic’ event which occurs repeatedly or might occur at any time:
... sad like after you get dumped by someone you didn’t really care about
... sad like when you pass a cemetery, seeing all those lonely gravestones
That's the sort of construction that's involved in your example.
The other thing that could be confusing you here is the use of have, which may feel to you like the beginning of a perfect construction. It's actually something quite different: neither a perfect auxiliary nor a causative auxiliary (as in to have something done) but the lexical verb used to mean “experience” or “suffer” and taking as its direct object a non-finite clause with a bare infinitive (an infinitive not marked with to) as its head. Thus:
She had her house burn down = She experienced her house burning down.
In the same way, you have your loved one pass away means “you experience your loved one passing away”.