When talking a bit earlier on about your thoughts during that separation you said
The distance allowed me to see what I really wanted and needed which was him.
I'm assuming that is still the case, please tell me if I'm off track.
To be left by someone is a very big deal, and as Tony mentioned he may have felt he was alone and in a position to seek another relationship.
Though you are back together, which is great, I'd think that his saying his biggest fear was you might leave again, when taken together with a self-knowledge he does not pick up on things, would give him a lack of confidence, even proper commitment.
One side effect may be a reminder he did have the ability to find another, hence the photos. A guess on my part I'll admit.
I would imagine if you both want to be together then you will have to come to an understanding, for example you take into account he may be oblivious to your needs and you may need to be forthright at the time and say "I need ...".
I find at times I have to ask my partner point blank what the matter is and what I can do. I too often miss what others might find is obvious.
It will be his reaction to that declaration of your need at the time which may be the pointer towards his commitment long-term.
To be fair I'd think you might need to ease his fears too. Pardon me if I seem a little blunt but saying "you need to give me a reason not to" does seem a trifle negative and even perplexing for someone who knows they have poor insight. I'd find it hard. Perhaps a bit of encouragement might help. Certainly saying when you were away you found you wanted to be with him would be one approach.
Please, I'm not critisising your very understandable words, just wondering about about my own reaction in the circumstances.
I hope this makes some sort of sense -what do you think?