Like Russ said, facing combative situations together creates a bond that can be rather difficult to understand from the outside. Every team sent out to face combat is rigorously trained so that they can work well together and understand to slightest cues for directions, movement, etc.
My father explained to me some of the training he was put through with a group he was given the chance to lead. You have to be able to pick up on subtle body language, as there is little to no talking when moving through a combat zone. You have to be able to trust that the people in your group will recognize and pick up on your cues and respond appropriately, and they have to trust that you will do the same.
An example my father shared of the extreme trust required was a situation where he moved directly into the line of fire of one of his men, took a shot, and then ducked down in time for his friend's shot. He knew he could trust this other soldier not to shoot him. Just imagine that! The absolute faith and understanding required to trust that someone is not going to shoot you when you move directly in front of them with no more warning than some sublte body language, if even that.
Now take a bond like this and a sufferer from PTSD - that sufferer will likely do anything and go anywhere for their combat buddy, and while the PTSD won't be gone, the sufferer will at least feel safe knowing that this person will pick up on his cues and protect him from any and all dangers, real or imagined, that they might encounter.
This is not a sign of lack of love for you. If anything, you can rest assured that this fellow Vet knows very well the love your husband has for you, and as a good friend will strive to do everything in his power to bring your husband home to you safe and sound after their outings.