AFL superstar Tim Kelly's fiancée and three sons have been abused by vile trolls unhappy he wants to leave Geelong and move back home to Perth.

Kelly, 25, requested a trade to West Coast on Wednesday hours before likely being named the Cats' best and fairest following a stellar 2019 season.

The midfielder's main reason for moving to his hometown is so he and his partner Caitlin Miller, 25, can be supported by family as two of their children are autistic.

However, some Geelong fans were not understanding of Kelly's family situation and sent cruel messages to Ms Miller demanding he stay put.

'Take ur (sic) fat, ugly kids home and leave Tim here,' one wrote in an Instagram message.

AFL superstar Tim Kelly requested a trade from Geelong to West Coast so he could have family help in raising two autistic children, prompting trolls to abuse his fiancée Caitlin Miller

Ms Miller was sent this message on Instagram hours after Kelly made his announcement, and responded with a joke when she shared it

But Ms Miller turned the disgusting abuse around by joking 'excuse me, only Trey is fat' when sharing the message on social media.

Kelly requested a trade to Perth last year for the same reason, though it was blocked by Geelong, which Ms Miller said prompted even worse abuse.

'This is nothing compared to last year, last year was horrible,' she told Daily Mail Australia hours after her fiance's announcement.

'Last year I got called a c**t, they wished cancer on me and that the whole house burned down with us all in it.

'I was sad then but now I laugh and think they are funny, they just look like fools.'

Ms Miller said she now responded to trolls with humour and tried not to take any of it seriously, such as in her response on Instagram.

'Trey has a big belly,' she laughed.

'We're just normal people like everyone else. You can't please everyone... we're a strong family unit.'

Elsewhere on Instagram, fans wished Kelly all the best, or politely begged him not to leave the club he was drafted into in 2017.

Kelly (centre) asked to be traded to West Coast, the team Geelong beat in the semi final last month where he was best on ground (pictured)

Kelly and Ms Miller have three sons, Tykeem, 3, and 1-year-old twins Tariq and Trey. Their eldest was diagnosed with autism last year and Trey earlier this year

Kelly's manager Anthony Van Der Wielen made it clear the Brownlow contender made his choice for family reasons.

'This is not a decision that Tim has taken lightly. I know he is forever grateful for the opportunity the Geelong FC have given him and he has enjoyed being able to represent the club,' he said in a statement.

'Something which I think we all agree he has done to the best of his ability over the past two seasons.

'It is well know by all that are close to Tim and his partner Caitlin that their young family are dealing with some significant challenges with two of their three children being classified as autistic.

'Tim and his family need to be at home surrounded by family and friends who can best assist them with therapy and support.

'After careful consideration Tim and Caitlin believe that West Coast can best provide the right environment for him and his family to prosper.'

Kelly and Ms Miller have three sons, Tykeem, 3, and 1-year-old twins Tariq and Trey. Their eldest was diagnosed with autism last year and Trey earlier this year.

Ms Miller in March shared how she realised Tykeem was autistic and how his diagnosis turned her into a disability advocate.

'Imagine being locked inside your body and having all the information in your head and not being able to express it? My poor boy deals with this every day. And it breaks my heart,' she wrote in an opinion piece for the Geelong Advertiser.

'As a mother there are things constantly running through my mind: will my little sweet boy ever attend a mainstream school, have a girlfriend, have friends, have a career, get his licence, ever say a sentence, move out, play sport and take after his daddy, ever be able to leave the house by himself?'

Ms Miller in March shared how she realised Tykeem was autistic and how his diagnosis turned her into a disability advocate

Ms Miller said she now responded to trolls with humour and tried not to take any of it seriously

The Aboriginal couple have dealt with vicious trolling before when an anonymous Instagram user left racist comments on Kelly's Instagram.

The player was labelled a 'monkey', and the since-deleted account also posted a photo of Kelly and Tykeem at an AFLX match, repeating the slur.

'It honestly breaks our hearts knowing that our son is only three years of age and is already being racially targeted,' Ms Miller said at the time.

Kelly is out of contract after his two-year rookie contract with Geelong expired, but is not a free agent under AFL rules and needs to seek a trade or re-enter the draft to move clubs.

West Coast is expected to offer a large haul of picks for one of the league's best players, along with a contract worth $5 million over six years.

Geelong is not giving up without a fight and signalled it would be more willing to negotiate with Fremantle, which has better draft picks, despite Kelly's request.

'Tim Kelly has asked that the club trade him to Western Australia, with his preference being to play with the West Coast Eagles,' a Geelong statement read.

'Tim is out of contract but is not a free agent. The club will explore all options in regard to Tim’s request.'