According to this article, this is the reason why he left: David has begun Montelongo Developments, run out of the same office complex as Armando and Veronica. One episode stated that Veronica has since taken the place of David.
Armando Montelongo Bio
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why is david montelongo no longer on flip this house with his brother armando?
It is because they were flipping a house called “cat house”. There were rat nest in the walls. Cats using entries house as litter box. Before they found the rats, David wanted to replace the sheet rock. He felt it would be bad to leave it up with the smell. Armando refused because would cost too much. So David walked out and said he did not want his name on a substandard flip. In the end they had to replace the sheet rock because they found rat nests behind the wall.
I read that was the split. They haven’t spoken since. I read that Armando is suing David and Melina for copying his business of seminars, bus tours etc.
I just watched the Cat House episode on the bio.com channel.