Again, definitive guidance can only be given by service medical professionals. As you will appreciate mental health issues are a significant factor with regard suitability in the Armed Forces due to the potentially stressful nature of the job in an operational theatre during conflict.
In order to manage realistic expectations the period of treatment and specific individual circumstances will play a significant part with regard future medical suitability. As a rough rule of thumb, providing the period of treatment was short, you can normally be passed fit two or three years after the course of treatment ends.
To re-iterate, the Medical Examiner cannot make a definitive decision until in possession of your medical notes relating to the condition and any related previous medical history.
Most people feel a bit down if they go through the break-up of a relationship, it's natural, not a medical condition. If the depression was serious enough to need treatment, then to put it bluntly, we ain't taking any chances.