To think this is dangerous driving?

[SidAndNancy]

Car trying to park (unsuccessfully) in horizontal parking space on the side of th road. One car in front of me goes around them.

I wait for the other side to clear to also go around them. No cars coming so I go around (about level now) when the other car decides to give up getting in that space and starts driving meaning I'm then stuck until I can move back over

Yes it was. The other car was not in the flow of traffic. If they wanted to give up on the space and drive off, they should have signalled, checked it was clear, and then driven off.

You really feel unsure about who was at fault here?

SidAndNancy

It was dangerous driving

However

Courtesy and safety dictate that following motorists wait whilst a parallel parking manoeuvre is completed

You should not have driven around

You are being unreasonable

Dangerous in what sense exactly?

It sounds inattentive and possibly inconsiderate.

Courtesy and safety dictate that following motorists wait whilst a parallel parking manoeuvre is completed

Where in the Highway Code does it say that?

I was taught that you wait for others to finish their maneuvers. But equally they should have checked their mirrors and waited for you to pass. You're both at fault IMO

How long would you wait for?

This was their fourth attempt at getting into the space.

By their 5th, 6th or even 8th you would have still sat there waiting?