Search Results: pays too much attention

So this is an on-going issue for me. My boyfriend is mostly good natured, kind and generally a good person.

But the thing that bothers me most is his lack of attention, focus and how he spends a lot of time zoning out during conversations. I've asked him if I'm boring or just not doing it for him, but he always says 'no, that's just the way I am, even with my friends' he also said he 'can't help it'.

I mean today we were out with my friends for dinner, so there were four of us at the table. But while waiting for food, my friend, her boyfriend and I sat and chatted. I tried to involve my boyfriend in the conversation as much as I could, but the amount of times I looked over at him to see him blatantly zoned out, staring into space and clearly not paying attention was just totally aggravating. He literally sat there, making occasional eye contact and giving the odd smile but said next to nothing.

It's embarrassing, it comes off as rude and I just don't get why this happens. When I asked why he was disengaged he said 'I was too busy thinking about food' - I mean, what? We were all hungry, but that didn't affect everyone else's ability to pay attention. Numerous times over the day I'd ask him something and he'd reply with 'what?' indicating he hadn't been paying attention.

I'm just getting to the end of my tether with it. He previously abused substances for some of his latter teenage years into his early twenties, as well as suffered minor head injuries due to sporting accidents - but can any of that explain why he zones out? I just need help with this, it really is bothering me.