But Lukaku would have to agree. I don't know any details about his contract, but Chelsea want to have a player in their team that is not willing to play the best he can and Lukuku can be a moody guy, which also reflects upon his efforts in a game.
Lukaku still really wants to be at Inter. And even he also rejected the very high salary offer from the Arab League in favor of Lukaku. Yes, it's true, Chelsea doesn't seem to suit him very well and indeed, the competence of the players is not only in their skills but also in their mood and attitude. Apart from that, it seems that Lukaku is quite suitable for Inter's style of play.
I didn't read about the salary that was offered to him, but it was probably substantially higher than he would have gotten either at Chelsea or at Inter Milan. But I think he is in a situation in his career where money still isn't everything and he wants to play a few more seasons in the Champions League and win some titles if possible. Not some titles in the Champions League, but in general. I guess he thinks that there were some misunderstandings in recent years that he wants to clean out from his chronology as a player. Inter Milan would be the best destination for him to do that and I still think that both the club and the player will do what they can to sort that out.