Inter intended to make a permanent move for Lukaku, but an agreement was not reached as Chelsea wanted a higher value than what Inter was offering. The inclusion of another team in the Lukaku transfer saga is also the reason why Inter are no longer serious about making Lukaku permanent, that's probably because other teams are willing to pay Chelsea more than the value offered by Inter.
Of course this is the fate Lukaku has had to endure right now after he really wants to stay at Inter next season. Lukaku will be with Chelsea next season although Pochettino has not included him in his list of plans for next season. Lukaku is potentially for sale, but probably not in the current transfer window.
Chelsea is desperately looking for the highest bidder for Lukaku. Inter wanted to get the Belgian striker at a very cheap rate but Juventus is willing to pay a higher price. Inter fans are unhappy that Lukaku is bargaining to move to Juventus, so they don't want him to remain in the club. They said he betrayed their trust because they had always supported him. I think he is considering Juventus because of the better package. But some Juventus fans also protested against the signing of Lukaku, making it plain that they don't want him in the clubs.
Currently, he is not part of Mauricio Pochettino's plans and he will not be joining the team for pre-season games in the United States, just as Hakim Ziyech and Pierre-Emerick Aubameyang. The Saudi League would have been the easiest route for him, but Lukaku has made it clear that he is not moving to the Saudi Arabian League so he has to wait to see if his transfer to Juventus will come through.