Lena Begum, 18, recorded a 3am voicemail message for Quzlam Ahmed saying: "You will probably love me one day the way I loved you, but it will be too late."
Minutes she was killed after walking in front of a van travelling at almost 60mph along the inside lane of the M65 near her home in Burnley, Lancashire.
Lena been treated for self-harming after carving her boyfriend's nickname, Kammy, into her arm.
A post-mortem examination showed Lena, from Brierfield, in Lancashire, died 'rapidly' from multiple serious injuries including fractures to her neck, skull, spine and ribs.
East Lancashire's assistant coroner, Mark Williams, said she was known to police after being reported missing a number of times and had previously been placed in local authority care.
She had started a relationship with Mr Ahmed after meeting him at a hospital placement in Bradford in October 2012.
In January 2013 she was asked to leave the facility following breaches of rules including drinking and later the same month, she was treated for self-harming after Mr Ahmed said he no longer wanted to be her boyfriend.
Giving evidence, Taslema Alom, who was with Lena the morning of her death, said: "I think she was mentally obsessed with him (Mr Ahmed).
"She would go and meet him whenever he called. I kept telling her to stop seeing him. Before she met Kammy she was happy and fun to be with.
"After she got with him, she changed. It was like he controlled her. I seen him punch her on one occasion, at the time of her 18th birthday."
Miss Alom said Lena had previously mentioned taking her own life. "I didn't believe that she would do it."
The night before she died, Lena, who was studying as a dental nurse at Blackburn College, had been at a friend's house and visited a shisha bar before asking to be dropped off near the M65 at around 1.30am.
As he recalled the last time she saw her, another friend, Marcia Khan, said: "Everything was fine. She was normal. She turned around and she smiled."
Police officers explained that between midnight and her death, 16 calls were made between Lena's phone and her mother's.
She also had two conversations totalling 30 minutes with Mr Ahmed, who was in Blackburn at the time, and recorded a voicemail message.
PC Richard Roberts, an accident investigator, said Lena would have been able to see the Mercedes Sprinter approaching her for 'more than 10 seconds' and that there was 'no obvious reason for pedestrians to attempt to cross the road there'.
Asked if street lighting on the M65 would have allowed the driver to have seen the teenager earlier, PC Roberts replied: "Potentially, yes."
Absolving van driver John Trainor of any blame, he added: "By the time she was illuminated, he (Mr Trainor) would not have had time to slow down."
He said that Mr Trainor, who was travelling at 59mph, would have been as close as 35 metres to Lena before he could see her.
Concluding that Lena had taken her own life, Mr Williams said her relationship with Mr Ahmed 'does not appear to have been very good for her well-being'.
He added: "It is quite clear that before 4am she walked across the path of a Mercedes van driven by Mr Trainor.
"There was nothing Mr Trainor could do."