Tell me lies......

I know he's lying about little unimportant things he thinks don't matter. He makes plans and forgets to tell me and then pretends he's just made them. Why not just say "forgot to say I'm doing x tonight" Drives me mental and I don't appreciate being made to feel like I'm going mad when I ask why he's behaving strangely, which of course is yet another lie!!!! Gah. I know I'm not going mad and I know when I'm being lied to. I know this is a symptom. I've asked him why he's behaving sketchy and he just denies it. We've been together 13 years, I know when he's telling porkies. What should my response to this symptom be?? Being pissed off and feeling hurt isn't going to help anything, I've given him calm opportunity to say he's just forgotten and that was met with another lie. I accept lowering standards on many things. But not where trust is involved. ***UPDATE SINCE ORIGINAL POST *** So I challenged him and now it's my fault! I've been accused of checking his phone (I don't do that) and still no admittance that he has lied! Now he's furious that I have questioned him. Obviously no talking about it until he is ready. I will not pursue as he has retreated.