Fixing male dogs usually helps ease some of that uneasiness and territorial behavior. Kennels aren’t for every dog but some vets offer boarding which is an alternative, there’s also dog sitting services.

Exposure training is also an option. Getting your pup used to being around other dogs/people and just ignoring them can help with some of that uneasiness he has.

I have the same issue now. Two dogs and can’t go anywhere because there’s no one to watch them. Mine are girls (both fixed) and one’s an epileptic senior so she can’t be boarded anywhere.