And it is understood that Shields, 51, was left with a broken heart after he bought her a ring but never proposed on their final dinner date.
Shields died at his apartment in Trump Tower, New York on Friday of what is now suspected overdose.
A source told Radar: “He bought a ring and took her to dinner to feel her out and it became obvious to him that she’d never marry him and it left Dennis heart broken.
“Bethenny could sense that he was going to ask her to marry him and it pushed her away. So he never took it out to propose but that was his purpose.”
“He was hoping the time was finally right but just as he got his hopes up he was shot down again, and that would be the last time sadly.”
It now appears that the banker was having a hard time coping with his ‘up and down’ relationship with 47-year-old Frankel and that it could have taken a toll on his health.
Despite the fact that he was still married to his wife, Jill, the reality star was the person he had his heart set upon.
A friend of the couple told Radar: “Dennis was head over heels in love with Bethenny, he died with a broken heart.”
On last week’s episode of RHONY Frankel announced that she was taking a break from Dennis saying: “I am going 90 days without talking to Dennis.”
While Shields talked about their turbulent relationship with Frankel on Mitchell Chadrow’s “Listen Up Show” podcast, which had been recorded on Saturday, August 4.
The source added: “Dennis proposed to Bethenny and she turned him down and he took it really hard.
“He was in love with her and not cut out for the unstable nature of their relationship.
“Dennis was often isolated and friends have been worried about him lately.”
Friends revealed that the couple’s relationship was “up and down” and this left Shields left “depressed and confused.”
The source added: “Bethenny would randomly stop calling Dennis and wouldn’t answer his calls for days, weeks, months and then he’d hear from her out of the blue when he had almost given up hope.
“Dennis was always there for Bethenny but it was always on her terms, when she needed him. Dennis took her back every time, that’s how much he loved her.”
RadarOnline.com revealed how the cast of RHONY had been told not to comment on the Shield’s shock death by bosses at BRAVO.
And, so far, there has been no comment from the Skinnygirl Cocktails mogul Frankel who was reportedly left ‘devastated’ upon earing of her ‘on and off’ boyfriend’s sudden death.
Banker Shields was estranged from his wife Jill after the couple split in 2016 before he started dating Frankel.
“Even though we did not live together, you still remained my nest friend and my husband. Not many people were able to grasp our situation but it worked for us,” she shared via social media after he died.
The Medical Examiner is still investigating Shields death in New York.