If humans suddenly lost the ability to lie, how many relati*nships would survive 24 hours?

it would convert to selective omission of information

I feel like everything is built on lies some way... That would be nuts.

Why were censuring relationships now?

I would lose my job so fast, holy shit

There is this great scifi series, The Academy series my Jack McDevitt where one of the few other highly intelligent species are telepathic, within a short range. They consequently can’t lie. They are very uncomfortable around humans even with the more gray areas of not telling something wholly untrue but just putting a spin on it.

You can watch that horrible movie The Invention of Lying if you like 

Watch Liar Liar with Jim Carrey (cant believe that movie is 30 years old next year) Its a funny insight into exactly what you are describing for one man and hes a Lawyer.

Ideas like this seem to assume a certain amount of being forced to speak or unable to soften phrasing. ("Brutal" is not a requirement of honesty.) I do think the impact would be significant societally, but I personally try not to straight up lie wherever possible. So the details are very relevant to the impact.  The only time I say things that are objectively untrue is when I'm feeling guilty for not returning communication and say I didn't see it. 😅 Oh, and I guess saying I'm "not bad" when I am bad, but I actually struggle with that outside of scripted-feeling conversations like being or serving customers. (Sometimes I will say to coworkers "oh, bad" in a cheery tone of voice then change the topic.) I do admit I think it would be funny seeing habitually dishonest people struggle, but they'd find a way. Definitely what someone else said about people adapting to lies of omission very quickly. 

Survival of the relationship isn't the issue, how many people would survive. I recently read a news article about a man who murdered his wife after she told him during a heated argument that his son wasn't really his but his biological brother.

It would be chaos. Lawyers wouldn't make it no more. The government would fall. Divorces would go thought the roof. Job loss would be at an all time high. Cheating wouldn't be cheating anymore. It would be like going to work. It would not be a good things. Lies are the bubblegum in the foundation. Without it, we'd fall apart.

None

Thats a great question. The omission of truth has been debated for a long time if its lying, like if you asked me what type of shoes Im wearing and I say "blue ones" instead of "nikes" am I technically lying?

If humans lost the ability to lie and only told the truth, there would be no need for lawyers!

You know, whether it's the *objective* truth or what one *believes* to be true both lead to some pretty interesting thoughts. For the former, we get into the semantics of what makes a statement objectively true (eg: off the top of my head, which option is morally superior in the trolley problem)? For the latter, that would be really problematic for people with low self esteem. They likely genuinely believe themselves to be worse than they actually are, and being forced to undersell themselves definitely doesn't help.

Short answer - not many

Why did you censor relationship...?

All those "I calls it as I sees it, take me or leave me" types would discover their "calls" are bullshit

man, it would be pure chaos, for real. people would be spilling secrets and exposing feelings left and right; some relationships might end while others might get stronger if they actually talk it out.