You are not on your own with this problem! Feather plucking is unfortunately quite common in parrot breeds and the causes can be numerous. Behavioural problems are of course the first thing we think of in these cases but this diagnosis can only truly be made once other causes are ruled out. If you are able to get to an avian vet, they will be able to rule out many of the illnesses and diseases that can cause feather plucking such as infectious, hormonal imbalances and pain. A blood test or X-rays may be required to do investigate the numerous possible causes.
At home you can rule out behavioural causes by ensuring that your love bird isn’t board (having a mate is great start!) but also ensure that there are enough tactile and visual stimulants and enough flying time, sunlight and access to a good bath or shower. Nutrition can also play a part so just double check that the diet you are feeding is complete and balanced. Allergies to certain foods can also contribute to feather plucking. Birds tend to be very good at hiding their illnesses until it’s too late so if you can possibly manage the trek to an avian vet it may be well worth the effort.