Hello, Here's a brief explanation: "What if they never liked me?" Conditional. In this sentence the action is over. There is a chance people did not like her in the past. "What if they have never liked me?"Conditional. In this sentence you can see an unfinished action that started in the past and continue to the present; the people who originally did not like her still might not like her today. I hope it helps!

What if they never liked me?- means What if all the time I knew them they actually didn't like me at all ( but the story is finished and in the past) What if they have never liked me?- means What if all the time since I have known them they actually have not liked me at all ( the story began from the past up till the moment of the realisation)