In conversation with NBA player Josh Hart on the LightHarted Podcast, Lukaku said United showed him little support in the final weeks of a difficult 2018-19 season.
"They had to find somebody (to blame)," the 26-year-old said prior to joining Inter in a reported £70-million transfer. "And I put my hand up. Like this year, I don't think I was the only one playing bad. A lot of people were playing bad, but they had to find the culprit. ... They had to find something. Whether it's (Paul) Pogba or it's me or Alexis (Sanchez), it's the three of us all the time."
Lukaku said he was expecting United to deny rumors of his departure when they first emerged. He wanted to be told he still had a future at the club. But Lukaku heard nothing and quickly realized the two sides had to go their separate ways.
"A lot of stuff has been said where I didn't feel protected," the Belgian added. "A lot of rumors - 'Rom is gonna go there, they don't want Rom' - and no one came out and shut it down. A lot of stuff was said for a good three, four weeks. And I'm waiting for someone to shut this down. It didn't happen. I'm like, 'OK, that's how it's gonna be.'"
Lukaku suggested United were responsible for feeding the rumors, which only intensified the feelings of distrust.
"You see all this shit coming out in the media. Who leaks it? Not me. Not my agent.
"I told them the rules. It's not good for me to be at a place where I'm not wanted. You guys have to find somebody to fit the system so I'm not the culprit all the time.
"If you guys really believed (in me), you would've said, 'OK, Rom, fight for your place.'"
Lukaku scored 42 goals in 96 appearances with the Red Devils.