I've (M, late 40s) been married 20 years, with the last 6 or 7 of these being as good friends who co-parent a child (10) rather than sexual or 'romantic' partners. We get on well, don't argue, and have created a happy and stable home for our DD, who has no sense that we're not more of a normal couple than we actually are. Nor do our friends or family. We socialise and go on holiday as a family, but also do both separately. It's not ideal, but it works just about well enough.
We've said to each other that if we wanted to see someone else* that would be fine, but that we will try to stay together for as long as we can for the stability this brings to our kid's life, and the pleasure we both get in parenting her full-time, and seeing her daily.
[*AFAIK, neither of us has actually done this.]
Recently, my OH (W, mid-40s) has become close to a single man who I don't know well at all but have met. She has 'feelings' for him. He's fresh out of a break up. They're currently just friends. He has a child a little older than ours, with whom our kid gets on ok - nothing special. He invited my OH and my daughter (but not me) to spend a weekend at his cottage in Somerset.
I objected to this because I didn't think it was appropriate. I had no problem with my OH spending time with him, given our situation: that was entirely her choice. But I was worried my daughter would pick up on any romantic vibes that may (but also may not) have been developing between them, and that this would confuse her. I also pointed out that if we ever did split up properly, and this guy was involved, our daughter might retrospectively reinterpret this weekend as a factor in the breakup of our household, and feel complicit or in some way involved. It might be a source of future resentment or guilt. We know we can't keep this up forever without letting our DD know more about our situation (my OH really, really does not want to tell her) but she's still v young and this would NOT be a good way to find out.
My OH feels I'm being controlling and overreacting to an innocent weekend away. So: AIBU?