The chart-topping singer, who died last month aged 48, reportedly began her romance with Jermaine, now 56, in 1984 - with their relationship inspiring the video for her 1985 number one Saving All My Love For You.
But according to The Sun Sunday, their fling ended a year later after he refused to leave wife Hazel Gordy - daughter of Motown founder Berry Gordy - to be with her.
The pair remained friends, with Jermaine - who was comforted by Whitney after Michael Jackson died in 2009 - reportedly shattered by news of her death and too upset to attend the funeral.
But according to The Sun Sunday, their fling ended a year later after he refused to leave wife Hazel Gordy - daughter of Motown founder Berry Gordy - to be with her.
The pair remained friends, with Jermaine - who was comforted by Whitney after Michael Jackson died in 2009 - reportedly shattered by news of her death and too upset to attend the funeral.
'Her death has devastated Jermaine because of the history between them,' a source told newspaper.
'No-one understood the scale of his grief because they didn't know what they shared.
Jermaine had previously hinted at a relationship with the singer in his memoir You are Not Alone: Michael, Through A Brother's Eyes, but said in the end 'we had to go our separate ways and it killed us both'.
His late brother was reportedly one of the few people who knew about their fling, but did not approve.
Whitney's body was found in a bathtub at the Beverly Hilton Hotel in Los Angeles on February 11. Investigations are continuing into the cause of her death.
Jermaine - who along with Michael was one of the lead singers of The Jackson 5 - and Hazel Gordy eventually divorced in 1988.
The singer, who converted to Islam the following year, married second wife Halima Rashid in 2004. He appeared as a contestant on the 2007 series of Celebrity Big Brother, finishing in third place.
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