Gosh, so many on here I could've written myself,....
Yes to the numerous trips to the shops - he was obviously calling her. One time he took a walk to our local shop and was gone for 50 minutes. I tried to call him on his mobile and it was engaged. He said he was speaking to his dad.
Even when we went away on holiday he kept having to nip to the shops or nip out to get petrol.
Lots of trips away with work. All bullshit - he was stopping with her. But he was always very convincing with his reasons, and used to have my doubting myself for worrying/feeling insecure.
Always came to bed late, always after me. Was sat downstairs texting her, avoiding me. I used to have to ask him when he was coming to bed.
Erratic moods at home - one minute nice as pie, the next critical, argumentative, distant, uncommunicative. Utterly exhausting, I never knew where I stood.
Like another poster said, when he was 'away' he always used to get in first with a text. To say hello, how much he was thinking of me, but that his phone was on low power so he'd contact me tomorrow. i.e. don't bother me for the rest of the evening Lou, and I've 'ticked off' my bit of contact with you.
Looking back they were all classic signs,.... and very predictable.