Hmm, well, not with every race directly. Would it be enough if that race was allied with another race wich is allied with me, and so be somehow being allied with me too?

In my game for exampe are the Klingons, the Jedi, and the Cardassians as (relativly)big Rivals. Im allied with the Klingons. The Klingons are allied with the Cardassians too.

Does that make the Cardassians Allies of me, through the Klingons? Cause Cardassians are allied with the Jedi too, and would be allied with ALL major races then !?

Don't think anybody but you can get a diplo victory.  My guess is that you got cultured into oblivion. That can happen even if you solidly control all your planets if another player gets a dying civilization event and has influence over a lot of unoccupied areas in the map.  Caught me off guard when that happened to me the first time, esp since it was an ally that did it to me.

You're warned as often as you simply click on the "Victories" screen and detect someone near enough to defeat you. Turn surrenders off or any other conditions but Conquest, maybe AI(s) will be gentle to give you a chance.

Something else to consider; of what i dubbed the 74.5% Influence syndrome by overly flipping the weak at random or by Galactic achievement and similar planetary improvements -- monitoring your own progress in any case (or specific situations) sometimes isn't enough.

Turns that you know about don't accumulate for nothing. Unforeseen effects included. With experience or instinctive knowledge of certain conditions, control becomes more evident by your strategic choices rather than simulation.

Wow, thanks for all the answers and suggestions, ill try them soon(bit busy right now).

Maybe quitting the Alliance with the Klingons will be enough, maybe i can cut some influence of the Cards or Jedi. The only bad thing is that my earliest save(an autosave) is 10 turns before defeat ...

Maybe that Victory screen can help me too ...., i just gotta find it

Thanks... monitoring gameplay status is the better part of any modders' strategy, reducing micman is the dream or reality of efficient players such as you, my friend.

I discovered a few jewels simply by clicking EVERYWHERE on the UI just for kicks... the Colonies spreadsheet alone is a treasure chest. Three buttons on a mouse, might as well use 'hem.

On the bottom of the "normal" screen there are many buttons in a row.  The one furthest to the right is the design ships button.  Toggle the next one to the left just beside it - I think that's the one - it has a lightning bolt?  That will take you to another screen which - IIRC - begins with what gov't you have, what party you have and some third thing. 

Along the top row of that new screen are several choice buttons.  One button takes you to timeline charts.  Another of those button takes you to the screen that shows your progress towards the various victories, like how many techs left to research for the tech victory, how much influence you have compared to the 75% needed for an Influence victory, how many alliances you still need, and how many empires you have still to conquer to win a conquest voctory. 

However, among those buttons on that top row is "colonies" or a similar name.

Toggle the "colonies" button and it will present all you all your colonies in a spreadsheet alphabetically top to bottom.  Each colony will have the table info of the column headers, which include mil production, social production, research, and $.  Also, it will show what is being built - both ship and improvement.  It shows the total number of improvement slots on each planet and how many remain unfilled.  It shows the population and if the planet has at least one ship in orbit.

I cannot imagine trying to manage an empire with more than a dozen or two planets w/o this screen!

The "ship in orbit" is itself huge, as one step when the time of war approaches is to ensure each planet has at least one ship in orbit to deny those early unsupported invasions.  W/o it, I find it easy on a large map to miss that one or more planets in my far-flung empire has no shield displayed on the galaxy map.

One of my favorite "tricks" or self-aids is to rename planets, in part because of this spreadsheet.  For example, when I get a 53% "Starship Bonus" planet, I rename it 53% Ship Bonus.  The # in the first character puts that planet ahead of all ones starting with letters.  Thus, on this spreadsheet, it puts it on top of the page.  That allows me to ensure I always have warships in production on those planets once I get them developed.

Yes, that's the one!

On focus, I favor the all-factories approach and use that screen extensively.  I can run down the chart and check/uncheck the effects of focus planet-by-planet to let me assess the trade-off in research gained versus time lost.  Also, as you said, one can order ship production there, and I find it easier and much faster from there than from the planet screen.

The spreadsheet is a lifesaver. It tells you 90% of what you need to know about any planet, and it tells you whether you need to check on that other 10% on the planet screen,.