AITA Husband spending time with a girl friend

AITA for being upset that my husband was taking a walk with a girl friend for hours and did not answer the phone. So a bit of context, my mother in law is away on business and will be gone for a few months. She has a cat that my husband goes to feed a few times a week . Four days ago he went and spent about 5 hours there. At around 11 a clock I was going to bed and called him to tell him that , no answer. He usually is glued to his phone and answers right away. I called him a couple of times then gave up and went to bed. Half an hour had passed and he called me back saying he didn't hear the phone. The next day I was a bit upset and asked him who he was taking a walk around the block with and he said the girl's name. I than told him that he never did this , let alone not answer his phone when I called. I have a feeling there's something going on there.

He says i'm overreacting and that she is an old family friend. So AITA?