A young man has been jailed for seven years for the attempted murder of a man he was intimately involved with.

In March last year, Joshua Christopher Tilmouth, 20, handcuffed and tied up Timothy Harkness, 36, then sliced his neck and stabbed him repeatedly.

The incident happened at Tennyson in Adelaide.

The South Australian Supreme Court heard Tilmouth was a scholarship student from Alice Springs and met Mr Harkness during a youth camp then started a relationship in 2011.

The court was told the pair organised a bondage and sexual fantasy session on the night of the attack and planned to use gags and blindfolds.

The men had purchased items from a sex shop and Tilmouth had bought a knife in the weeks before the attack.

In sentencing submissions, Tilmouth argued he was driven to the attack after learning he unknowingly had engaged in repeated sexual activity with the victim while he was asleep or too drunk to remember.

He said he only became aware of the sexual activity after Mr Harkness sent him graphic text and Facebook messages.

Justice Michael David rejected that notion, saying it was inconsistent with the evidence before him and it defied commonsense.

"This is a most sad and disturbing case," he said.

"How could a young, high-achieving, well-educated young man from a supportive family act in such a way?

"It appears to me the only plausible explanation, on the material before me, is that you were young, you were confused about your sexuality and this built up into a well of resentment towards your victim.

"This was a violent, serious and premeditated offence. There is no dispute that you had planned it for some weeks."

Tilmouth was jailed for 10 years with a non-parole term of seven.