Near the end of his time in the force, he discovered his long-term partner was having an affair with his platoon commander.
Her infidelity was common knowledge among others in his camp and "unsurprisingly" caused him "significant distress".
To cope, Doyle began drinking heavily on the weekends and using MDMA.
To fund his drug use, he began dealing the drug to friends, including other members of the military.
At sentencing in June last year, Judge Northwood refused to grant a discharge, finding his offending was of a moderate level and commercial in nature.
He also considered it an aggravating factor that he sold MDMA to military personnel.
However, Judge Northwood took into account his early guilty plea, age, youth, loss of career in the army, his efforts to rehabilitate as well as the military proceedings.
He found that he didn't accept Doyle did not have transferable skills and he could still pursue a different career choice. He would also not be affected by travel or gaining professional registration.
Doyle's counsel, Roderick Mulgan, submitted to the Court of Appeal that Judge Northwood overstated the gravity of his offending and that it happened "in circumstances of
exceptional personal upheaval".
He submitted the NZDF compounded his emotional distress by failing to appropriately manage the issue.
Doyle's evidence was that he had invested significantly in his relationship, particularly by providing financial support, and her infidelity left him distraught.
"Mr Doyle's evidence was that this was common knowledge within his army cohort.
"He said that it was incredibly difficult enduring their gossip and laughter.
"He said that his platoon commander had a reputation for behaving in this manner."
Doyle also commented that it was devastating to be forced daily to obey orders from his partner's lover and call him "sir".
He claimed the NZDF was callous in its management of the issue when asking for a transfer, and was told to "harden up".
In making their assessment for the appeal, the court judges agreed his offending was moderate and was properly characterised as a street-level dealer.
While the court accepted Doyle notched up "seven years of commendable service to the NZDF", his offending breached his employer's trust and revealed a lack of discipline.
"Given the moderate gravity of his offending and the relatively minor consequences to his
career prospects, we are not satisfied that the consequences of a conviction are out of
all proportion to the gravity of his offending.
"While it is impossible not to feel some sympathy for Mr Doyle and the unenviable predicament he found himself in, we do not accept that these circumstances may be pressed into service as mitigating factors to the extent Mr Mulgan advances.
"As noted by the Judge, Mr Doyle is 'not the first person' to use drugs to escape
emotional issues and descend into drug dealing."
The court did not find that the judge overstated the gravity of Doyle's offending.
Doyle had already been discharged from the NZDF, a decision that was final, and made from the offending which underlies his conviction.
"This position is quite different from someone intending to pursue a career path in the NZDF where a conviction would operate as a bar."
"Experiencing some difficulties in obtaining employment and advancing a career while a conviction is fresh is not an extraordinary consequence of the conviction," the court of appeal decision stated.
Doyle had since gained a new job elsewhere.
"Ordinarily, offending involving dealing in drugs is considered too serious to permit granting a discharge without conviction.
"That is not to say that the legal test can never be met.
"This is not one of those cases."
Doyle's appeal was dismissed.
