No, there were no extreme tensions between the nations, you could say without problems that you're Croat or Serb or whatever and you could move freely and safely throughout the country. Whoever says today otherwise is lying through their teeth. Nobody would mind really. I'm an older guy, have relations on many sides, have travelled through all corners - people were really welcoming, nice, a guest was a king in their house. People would make jokes about stereotypes about other nations, like Montenegrins being lazy or people from Bosnia being slow, but they were not malicious. And everyone could take a joke, ffs - not so many snowflakes like today, mortally wounded by smallest silly thing.

It was not like some fragile peace which Tito was holding together and when he died, it was open season. Mind you, he died in 1980. and shit hit the fan in 1991. After the war people see it just through the nationality prism, because that's how the federal state ended. But it's not how the dissolution started and it was not how the life problems in the country were set. The main problem in the country was political - the ability to express different way of political thinking, not expressing one's nationality. And it was the main problem because it covered the whole country, not just parts of it that might have wanted out or not. Then the second wide problem was the class issue. Which sounds funny in a country that should not have different classes. But it had - the elite, thanks to their political might kept the most lucrative positions (like running the companies) for themselves achieving the financial gain, of course, and wide majority of people hated them for it. That's the problem that persisted even after the dissolution of the joint state and is very alive in the region today. And then we come to the national problem, which wasn't that prominent throughout the whole country - that's why other people are posting here how people were surprised that it escalated quickly and they did not expect it (which is how I remember things too). I mean, we all felt something was happening, the cold was was ending etc. But it was more of a feeling it's going to happen along the social construct, how economy was structured, considering how increasingly lax rules were of late. Like, you were allowed to own a small private business etc - interpreted as small steps to dissolution of the socialist political system.

Anyway, there were some dissonances in Slovenia and Croatia regarding membership in the federation and the conditions under which they entered. I remember we learned about it in school (at least in Croatia, where I went to school), so it wasn't hidden. But it was pointed out that it happened in previous state, the Kingdom of Yugoslavia, when not so rosy things happened. The official policy was, that in current federation people remained out of their free will. I have to admit, I never felt or heard widespread talks about independence or whatever. There were some other problems described above. There were people in Croatia who were in partisan movement, who wanted to live in, then socialist republic. And there were also people who were on the losing side after WW2. So it wasn't really the situation where every Croat was secretly united in a rebellion or whatever and just waited to jump. That's just bullshit, even if today's schoolbooks describe it so romantically. Schoolbooks are written by political establishments in every country in every moment of history, the way they want the history to be seen. There were a national movement in Croatia in the late 60s, early 70s, called the Croatian Spring. Which started because of the money, as usual, where reformist and conservative fractions of the party collided. The whole issue was about financially helping (or not) other republics, which were not doing so good. I mean, we see the same argument even today in federations (democracies!) when the money gets tight - "we earned this money, it should stay here". And it escalated slowly from that point until it was shut down.

Fast forward to the 90s. Communism fell, free elections were there. Issues with the communist elite class seemed gone, problems around voicing other political thinking also gone, obviously. Almost all new political options were nationalist. The more they distanced themselves from the previous regime meant there were more suited for the job in their eyes. Some of them went to extremes, following this logic. Felt similar to the rise of populists today - it's easy to spread fear in people and offer yourself as a sole saviour, playing on division between people. The loudest options won and it escalated quickly. Hence the surprise of (the most of) the people when it happened.