I do see this as a possibility. However, he did confide in a girl from work shortly after we separated. I saw emails they sent back and forth. He was just saying that he felt so sad about life and not happy with his marriage and she was complaining about her married life (she just got married in October). If he wanted to be completely alone, then why would he confide his feelings to her??
There could be any number of reasons for this, only your H knows for sure. One possibility is that your H doesn't feel the fear of judgement from someone whose opionion of him wouldn't bother him if it were negative (like yourself or his mother). Perhaps your H has found some common ground with this coworker, in that she understands his position of being unhappy in a marriage, if she's living in one herself. Whatever the case may be, nobody has a crystal ball and is able to say what's really going on inside your H's head. Only he knows his reasons. But I feel I must warn you to be cautious about making any assumptions or jumping to any conclusions. How does the saying go? It's best to avoid jumping to conclusions, otherwise you could fall & hurt yourself. Something like that. My point being, to be careful about making any assumptions as it can sometimes lead down a path of anxiety.
As for the dog, again, only your H knows the answer to this. But I suspect that if he is depressed, the dog probably doesn't even fall under his radar. On some level he knows you're available to take care of it & will, so he's able to let go of any responsibility he feels towards it while he's feeling this way.
M:36 WAH:41 M:16 T:17 D:12 SS:21 Bomb: IDLY 10/29/11 Separated same day, about an hour after the bomb.