20 year old Marcus Webb discovered the body of his girlfriend Ashli Blake, 15, in September at the foot of a historic monument near Rockbourne, Hampshire.
Prior to her death Ashli, who had a history of mental health problems, had sent him a text message threatening to 'jump off the tower', the inquest heard.
Today Hampshire Police confirmed a 20-year-old man, confirmed as Mr Webb by his father, was arrested on November 25 on suspicion of child sex offences.
He has not been charged with an offence and was bailed until February 6 while investigations continue.
Winchester Coroner's Court yesterday heard how Ashli, who was born with the surname Cook, was found dead by her boyfriend in the early hours of September 21.
She sent a text to him which read: 'I am going to jump off the tower.'
Mr Webb told the inquest he had not believed her threats at first, because she had made similar comments previously.
But he launched a desperate search when he and her family failed to get hold of her on the day of her death.
Mr Webb said he had visited the monument several times with Ashli.
In a statement read to the inquest, Mr Webb said: 'I feel so guilty and I feel like it was my fault, she told me she was going to kill herself and even told me where she was going to do it and I laughed at her because I didn't believe her.'
'Ashli meant more than life itself to me, I would do nothing to hurt her, I now feel there's no reason being here.'
Ashli's mother, Canasta Blake, 37, told the inquest in a statement: 'They had made plans for the rest of their lives together - at 16 she was going to move in with him.'
'She was besotted with him. She was always worried about him and what he was doing.'
'I do not understand why she did this, she had everything to live for and often spoke of the future. '
The coroner was told Ashli had suffered 'some bullying problems' at Burgate School in her home town of Fordingbridge.
And Ashli's GP, Dr Charlotte Hillsley, at Fordingbridge Surgery, said she had suffered from low moods and sleeping problems.