Giving evidence during the trial, Keene said that throughout their two- and-a-half year relationship, they had constantly switched from being incredibly happy and planning a future together to heated arguments where Gaby would threaten to leave.
On the day of her death they had had a heated row about him staying out late with friends, after he had taken part in the Bath Boules tournament, and she had told him not to come home.
Keene arrived home at 10.30pm, when a tearful Gaby phoned the couple's friend Ben Jones to ask him to collect her partner because she did not want him in the house.
The call, which ended because Mr Jones' train went into a tunnel, was followed by another where she left a harrowing eight-minute voicemail in which she could be heard screaming, sobbing and pleading with Keene to stop.
The recording, which was played to the jury, ends with the sounds of her being punched and choked and then silence.
Keene then spent the next hour and ten minutes sending a text message from his phone to Gaby's, asking her why she had stormed out and gone for a walk, before then sending messages from Gaby's phone to Mr Jones saying she was fine.
He also attempted to clean up the blood before finally calling the emergency services at 12.12am.
Gaby's body had severe bruising to her face, forehead and head, and the prosecution said she was strangled with both a dressing gown cord and a piece of electrical cabling.
Keene admitted that the text messages looked like he was trying to cover up the killing, but told the court he did not remember a lot of what had happened.