I have a very large breed 15 month old female dog. She has started being quite territorial (barking at dogs that come past the house), snapped at my older small dog the other day when I gave them both a treat). A month ago a small dog went for her when she was on her lead. Since then she has been lunging and barking at other dogs when she is on her lead, despite being ok with the exact same dogs when she is off lead. I feel like I cant take her out as much as I used to (to cafes, in the middle of town etc, she still gets her exercise and off lead time away from other dogs). The other issue is that she is bored I think, I walk her 3 times a day, do training and games with her during the day, and take her to classes. She was so happy staying away a few weeks ago when she stayed somewhere with another large dog. I feel like I am failing her and she would be better off rehomed. But it is breaking my heart. Am I being stupid?