Hi Bobby,
This is hormonal behavior. Lovebirds are very territorial, and will guard anything they view as a nest. Actually the females are the more aggressive & territorial, and from what you describe, you may have had a female, although some males will act this way. While it seems cute, we now know more about the issues hormones can cause for pet birds, so it’s best to avoid things that trigger hormones. With males, hormones can cause behavior issues like aggression. But there are also physical risks including prolapse, and nutritional problems if he starts to regurgitate on toys or people as a sign of affection. Some males can get so obsessed with a toy or mirror, they stop being active or playing with toys or interacting with people. With females, prolapse is also a concern, but the main concern is egg laying. Many single female pet birds start laying eggs and won’t stop, resulting in veterinary intervention. So the general advice these days is to avoid letting a pet bird have things like boxes, bird tents or huts, bags, etc.
Thank you for asking Lafeber,
Brenda