You're helping him too much. My dd was like this...she's also 8. I was always trying to make it easier and faster for her....in fact, the best thing I could have done...and did do...was to make her sit down on a Friday, half an hour after she's got in from school...and do it alone.
She knows I will help if she asks...but she just gets on with it. If he doesn't then let him go in without...the teacher might make him do it in playtime. He might not like that s he'll eventually get the message.
There. I hate homework. DS is very bright and has a very biased mother who says he is very bright...but homework!!!! He can do it easily but will he do it?! Hell will freeze over, the dog will lay hens eggs, the pope will become a buddhist but 8 year old DS will not do his homework. Major tantrums, shouting, screaming and so on. He has told me what he wants to write (5 sentences, not a massive amount) and I've written it down (when waiting for a sibling doing a swimming lesson) and he just has to write it in his book. I've told him that if he doesn't do it then I will write a note explaining that he has refused to write it in his book and let him face the consequences at school. How do you deal with homework refusal?