The issue is, he feels his contribution is far greater than what it has been and clearly seems he feels he is bigger than the club.
This recent interview (mental health issues aside), the Instagram post the last Goodison game followed by his mrs instagram posts, the fact he downed tools last summer when he was expecting his big move and refusal of signing a contract.
Good luck to him wherever he ends up, but I would be heavily surprised if many teams come in for him and there will be no-one from the top half of the table at least.
It is time for both parties to move on!
Think it all stems from the need to be loved by the fans, or the feeling of having to be accepted.
People like Ashley Young got it, or understood it. (probably a main factor of him playing at the top level for so long) Your never going to get the credit or love you feel you deserve if you are searching or in need of it constantly
Its easy to say he should be confident and satisfied with his contribution (he's scored winners to keep us up, derby goals, played for England etc etc), and from what you hear from him in his academy days he's worked very hard to get were he is.
But he needs to do it for himself and himself only, Lukaku never needed the number 9 to feel validated as the main Everton Centre forward, as much as Dom talks about how privileged he is to wear that number etc..........again its another cry for him to be loved, which i think stems from Duncan mentoring him, his goal record is better than Dunc's but its not just Duncan's on the pitch stuff that has had him idolized.
He had an 18 month purple patch similar to what Bamford had at Leeds and Solanke had at Bournemouth, but i think he would be much happier and secure in himself if he moved on to somewhere were he can feel comfortable in himself and football isn't as 'important' to him. I think going abroad would be the best thing for him to do.