How to ask him to talk to me more (again)

Alright so my boyfriend is a crew chief in the marines and works close up to 12 hour most days. So needless to say he has long days and I understand that there’s really no time for him to talk to me during the day. I also get that the weekends are his time to blow off steam and catch up on sleep. During the weekdays after he gets off, that would typically be the time we could talk the most. But that doesn’t always happen, sometimes there will be hour gaps in between texts. That’s hard for me because we have to do distance for the next year, and sometimes I really miss talking to him. I brought how this is kind of hurting me and he was super sympathetic and admitted that he wasn’t making enough time for us. It was great for a few days but now that the work week is starting up again he’s slipping back in to his old patterns. I guess I just wanna know how to bring up that this is still upsetting me without being a nag, or without ignoring the fact that he’s around people all day and deserves to just turn his brain off from time to time.