Chronic Misunderstandings...he has different meanings for certain words?

My fiance & I had quite a weekend of misunderstandings. It ruined the possibility of spending time together, twice. Part of the problem is that he very often forgets about plans that we've made, or forgets the time we decided on meeting & then doesn't manage his time well beforehand to make sure things go as scheduled & so we end up having much LESS time together. Or, thinks we didn't even MAKE plans at all. This frustrates me because we had talked about what we would be doing later that day, but he completely spaces it. He says things like "it wasn't clear to me that we were actually doing something. I didn't think they were solid plans." My question is, "Why do we say we're going to meet around such & such a time if we're not???" Another issue is that certain words seem to have different meanings to him than to the rest of the world. For example, the word "get." When he asked me if I was coming back to his house after work on Saturday afternoon, I said, "Yes, but I will need to go home & 'get' my boys first." (We both have children). He took this as meaning that I was not coming over, but that I was going to have to stay home with them. (?) When I contacted him later that we were on our way & he answered me that he & HIS boys were already busy doing something & we couldn't come over, needless to say I was surprised & dismayed. In my confusion, I reminded him about our conversation that I was coming back after I went to "get" my boys. He told me that when he says that he has to "get" his boys, he means that he has to spend time with them. *Sigh* I responded, "Well, yes. But that's because you go 'get' them @ school or @ their mom's & then BRING them to your house to be with them. I had to go "get" my boys at my house to BRING them back to YOUR house with ME." (FYI, my boys are old enough to stay home alone for a few hours). I just don't understand how "get" can mean "stay home with" to him, especially combined with the other words they were said with, like "yes I am coming back." Ugh. These disappointments happen ALL the time... Anyone else have similar issues?