The American bar owner entered the house on Wednesday night, but decided he did not want to remain a housemate if Noirin was no longer there.
He packed and left on Friday night shortly after Noirin’s departure.
“I’m definitely leaving,” he told Bea following the eviction. “I just didn’t feel like running after her, I want to go out one at a time.”
“I don’t have a reason to be here,” he added. “I hope whoever wins deserves it, it’s not an easy experience.”
Earlier in the evening Noirin said in her eviction interview that Isaac would not stay in the house now she had gone.
“We made a decision that he’s not going to stay,” she told Davina McCall. “The only reason he came here was to be with me and get me away from Siavash.”
Isaac is the fourth housemate this year to leave the series voluntarily.
Single mum Saffia quit early on in the series, while Karly’s boyfriend Kenneth walked out last Friday after just a week in the house. Tom – who joined at the same time as Kenneth – also quit last weekend.