I ( F36) met MIL for the first time a few days ago. Before the actual meeting, I had viewed her as the sweet woman who made sacrifices as per my boyfriend’s stories ( Tim, M39).

We attended a concert, and he suggested that we stay at her place. I didn’t want to but he insisted and I gave in. He had told me that his mom was his first love but I took it as a Hallmark kind of remark.

I spent 2 days with his whole family. I liked almost everyone but I was left feeling weirded out and confused by his and his mother’s displays of affection.

As background, MIL was cheated and abandoned by FIL. She, Tim and the rest of the siblings are quite close to each other.

He kept hugging her, which I honestly thought was very cute. But they started touching foreheads, he slapped her butt and she “playfully” tried to pinch his crotch. There was a moment when he nuzzled her neck and made puppy sounds. I honestly don’t think they have had any carnal relationship but I shut down after seeing that. Specially when he said that he recalls her butt being very rounded when he was a kid.

I was so mortified that I packed and left while everyone was asleep. He has been asking what’s going on. So far, I made up a story about why I left because I don’t even know what to say because it could turn out to be a terrible accusation.

My idea of him has been negatively altered and I want to end it but I know I need to explain why and this makes me extremely uncomfortable.

Edit: Wanting to clarify, he and I are in a serious relationship but not married. We are both divorced.