If Arthur had just left things as they were, he'd be free. He shouldn't have broken his holiday and shouldn't have taken Maggie out of the nursing home, even if it was only for a drive. Once back in her own house, the rest was inevitable.
It wasn't all Robert's fault. If he hadn't upset his mother, Arthur certainly wouldn't have brought the budgie home, but the ten naked dentists dancing on a golf course at midnight would probably have been arrested anyway.
Funeral arrangements are always trying, so Maggie decides they should do a few trial runs of Arthur finding her dead in her bed. But she panics about dying, before deciding its time to start planning her own funeral.
All Arthur wanted was a quiet Saturday. But Maggie remembered the clock. The one Leo gave her on their 25th wedding anniversary, and it had no business being in the house across the road. She didn't steal it. It was hers to start with.
Arthur had no-one to blame but himself, really. Respite care for Maggie was all his idea in the first place, but he didn't expect Maggie to arrive home at that time of night or in that condition.
A baby in the house is the last thing Arthur expects to find when he arrives home from work. Whose baby is it? It's certainly not Maggie's, but it could conceivably be Robert's. Unless, of course, Maggie kidnapped it.
A good old fashioned Sunday roast lunch with the family so Arthur could introduce his new girlfriend probably seemed like a good idea at the time. But Arthur should have known better and he should never have lied to Maggie about Meredith.