Dd is 7, dp has been around since she was one. Recently she's been really off with him - not wanting him to take her to school, hold her hand,read to her and so on. She'd rather miss out on doing something she enjoys than do it with him. He seems to just grate on her. For example, if her breakfast is ready I'd tell her so, if she didn't go to eat it within a minute I'd check she'd heard then leave her to it - her own fault if it goes cold, though 99% of the time she goes within a couple of minutes.
Dp on the other hand would tell her it's ready, then keeping saying 'come on, breakfast is ready' every twenty seconds until she gets annoyed or even try and lead her to the table. She is very headstrong and likes to do things on her own terms but he just doesn't seem to get her anymore. By his method she usually leaves her breakfast then he'll offer her something else, so it isn't that I'm pandering to her - quite the opposite.
Today dp took our dd (14 months) out for a few hours as I had some work to catch up on. He then collected dd from school and took her to the dentist. When they returned I had cooked tea, I washed up, tidied, sorted out school bags, bathed the kids, did homework with dd, read stories with them both etc. He watched football and/or sat on his phone.
When he heard me telling dd2 that it was the last story I heard him creep upstairs and go and sit on dd1s bed as she'd been playing in her room. When dd2 and I entered dd1 glared at dp and said: 'i don't know why you're pretending you've been playing with me, mummy knows you've been downstairs on your phone you know.' He mumbled something about tidying up and she started ranting about how he hadn't tidied up, or washed up, or anything else because I'd done it as well as everything else while he played on his phone 
She then proceeded to tell him that all he'd done that evening was upset dd2 by making her have tummy ache because all he'd fed her today was two lots of chips and a packet of crisps and by turning off the iPad quickly when he heard me coming downstairs so I wouldn't know he'd stuck dd2 in front of igglepiggle 'yet again.' I honestly never rant to or about dp so this tirade hasn't come from me.
Dp looked shocked and had a go at her for being a 'completely disrespectful little madame' and turned to me and said 'are you going to let her speak to me like this?' Dd2 was then sick so I had to sort her out but I could hear her and dp still bickering. I put dd1 to bed and said we'll talk in the morning as dd2 is still being sick and dp gone to work.
Aibu to have let her speak her mind? I feel it might do her good to get it off her chest as the resentment has obviously been building but then feel I'm undermining dp. However, everything she said was true so I can't tell her off for that. Maybe just speak to her about voicing her opinions more respectfully?? What do you think?