Always late!

I'm really big on punctuality but I'm understanding and let things slide but my SO is always almost late. I mean, I love him so much but this is so hard to keep ignoring. I've asked him to pick me up before and ended up waiting over an hour for him. If he says he'll be at my house at 7, I know by now not to expect him until 8, if I'm lucky. I get mad at him for it all the time and I've talked to him a out it and he's said he'll try to be more on time but it just keeps happening!! What am I supposed to do? I try and try to let it slide but he's driving me crazy.