The actions of Drew Francis Thompson, 28, following the break-up were described as "productive of terror" by Acting Justice David Robinson as he handed down sentence on Friday.

Thompson had repeatedly and naively tried to win back the online match he first met on dating site eHarmony in March 2013.

His efforts persisted until October, when she agreed to meet him at Dickson shops.

That very public meeting, Acting Justice Robinson noted, was "not a success".

Even the woman acknowledged at trial that she was cruel to Thompson, yelling at him and telling him he was "boring" and "too simple to be her partner".

A month later, he put on plastic gloves, grabbed an unloaded gun, broke into her apartment, and hid behind a door in her spare bedroom.

As she walked into the room, he sprung out and covered her mouth with a gloved hand, telling her not to scream.

The woman says she can still remember the smell of the glove to this day.

"That situation is immediately productive of terror," Acting Justice Robinson wrote in his sentencing remarks.

"The terror continued when the young woman was forced onto the bed with the gun resting on her naked chest."

The pair sat and talked for some time, until Thompson eventually left three hours later.

The woman, who thought she was going to die, went straight to police.

Thompson ran from officers when they turned up at his home, but was arrested. He was found guilty by a jury last year and faced the ACT Supreme Court for sentencing.

Acting Justice Robinson said Thompson had good prospects for rehabilitation, given his lack of a criminal record, good support from his family and new girlfriend, and improved mental health care.

Thompson, he found, had suffered from a depressive illness when the offences occurred.

But the court could not find his actions were a "cry for help".

"I cannot make any precise finding as to why the offender was motivated to break into [the victim's] apartment in the circumstances in which he did on that day," he said.

"The most likely explanation to my mind is that he wished to impress upon her the gravity of the distress that she had inflicted upon him."

Thompson was sentenced to a total of two years imprisonment, which is to be suspended from December. He has already served one month in prison.

Thompson will be required to sign a good behaviour order for two years and accept the supervision of ACT Corrective Services.