Please can I have your opinion on this domestic

[Plikujyhtg]

Parent A
Parent B
DS (7)

DS 7 had a friend come round to play after school. Unbeknownst to Parent A and B, friend had gone into the parents' bedroom and jumped up and down on the parents' bed. DS didn't stop the friend, although insists he didn't join in.

When friend went home, Parent A was annoyed that DS didn't stop friend from entering his parents' bedroom and jumping on the bed. Parent A told DS that they couldn't watch the football on the TV that evening. DS was upset and cried for 5 mins. Then was fine.

The above is just some background context for the following:

Half an hour later: Parent A and Parent B are upstairs with DS and getting him ready for bed. Everybody's mood is fine.

Just before getting into bed, Parent A plays a game with DS. Parent A won't play the game the way DS wants them to. DS gets upset. Parent A refuses to back down.
Parent B intervenes to calm DS down. DS calms down and says he wants to watch football. Parent A says that no he can't due to earlier events with friend. DS gets upset and starts crying. Parent B tries to calm DS and regulate his emotions before bedtime. DS is still upset and whining. Parent A says "I'm going to kick off in 30 seconds if you don't stop. Do you want me to kick off?"

Parent B is aware that Parent A's kicking off means shouting loudly and getting angry. Parent B says "ok guys let's tone it down".

Parent A is now angry with Parent B for undermining them and left the bedroom annoyed.

Is Parent A justified to be angry with Parent B?

Another one for the Why All The Attacks On OP camp.

As for the 'undermining' BS, if one parent starts to be very unreasonable you either step in or become complicit. I find 'don't undermine me' can definitely used to control someone into not questioning cruel or unreasonable behaviour.

Parent A sounds like a dick, how is there debate about this?

This!

Parent A is a disgrace!

I wouldn't support my partner either if he was threatening to kick off/lose it. I have told everyone, including him to calm down when things have got heated. If you aren't going to behave like an adult, and keep control of your temper, then I will not support you. It's a choice, especially if you announce it's going to happen!

I find 'don't undermine me' can definitely used to control someone into not questioning cruel or unreasonable behaviour.

100%.

Blimey my husband, sorry parent A would've been jumping on the beds with the kids. Lighten up.

Children jump on beds. It's not worthy of a punishment. Maybe a telling off and a make sure it doesn't happen again.
Really, parents should be keeping an eye on two 7 yr olds.
Poor kid having such a shit parent A.

Op you are obviously parent B I don't know why there's so much criticism of you some people clearly want to have a go.

Your dp is an arse yes there should be consequence for ds allowing a friend in to your bedroom but I would probably pick something related like friend not allowed over until ds can be trusted. Friendships at school are tough and your ds probably felt pressured and it was easier to allow it and hope to get away with it than challenge it.

Your dp is wrong to lose their rag with ds they need to work on managing their emotions better to set a better example.