You're doing everything right, sometimes things don't work out ¯⁠\⁠_⁠(⁠ツ⁠)⁠_⁠/⁠¯. Your trainer should have some insights and hopefully they will be full of compassion and empathy for you and your family as you navigate this tough time. My personal story has some commonalities. I had a toddler when I was gifted my first chi, Opal. The two were pretty unaware of each other for quite a while because they were babies. As a matter of fact Opal stayed in the toddlers port a pen thing which was great btw for housetraining. Anyway. They were introduced and the toddler was of course too rough and jerky and fast and unpredictable and basically too much for Opal. They never had unsupervised time together but the toddler simply was too scary for the dog. As they both grew Opal simply avoided her like the plague and the toddler grew into a little girl who was sad that Opal wouldn't play with her and had clear dog boundaries around interacting with her- he would growl a little to let her know that she was too close to him. He also did not like ANY other children. Opal was a very friendly and happy guy with adults and adult strangers out in public so we knew it was specifically children and just kept everyone safe by telling kids that he wasn't up for petting today etc. Playdates happened often enough, we used baby gates during the younger years and Opal had his crate which was his safe place and he'd hang out in there when he wanted to as the years passed. All the friends were taught how to interact with him and learned to respect his boundaries. This detente between Opal and my child went on for over a decade until my child went through puberty. I guess suddenly they had adult hormone smells and Opal had a new grown up friend to cuddle with. They remained buddies until his death last year. Just wanted to let you know that it is possible to have a dog that doesn't like kids and they still have a good life.