I would like to add that my dogs, also 2 boxers, are like my children also, there's nothing I wouldn't do for them, believe me when I had my first boy neutered at 6 months, i sat outside the clinic for half an hour wondering if I was doing the right thing. And after thinking logically, for his health, I knew I was. Behavioural issues aside, neutering has so many health benefits, reducing the chances of having an enlarged prostate, which in some cases can become so enlarged it can interfere with bm's, Testicular cancer and so on...
There are so many unwanted dogs and puppies in the world that in my opinion unless your dog has a reason to be - like he is a conformation show dog - there is no reason not to neuter him. Helping to prevent more unwanted puppies in the world. Aswell as ensuring he will benefit health wise from the surgery. I hope that you do decide to neuter your dog, for his benefit, and just know that if you take him to a veterinarian that you trust, I'm sure he will be well taken care of and they will put your worries aside and make you feel confident you are making the right decision for him. Good luck with whatever you chose, and I am very biased but Boxers really are the the cutest and most awesome dogs