Allied status disappearing without warning

ok, added it to my list

In that case becoming allies should also be a pop up event.

I personally think that allied status should be a treaty event and not just automatic if your relations are good enough.

Perhaps once your relationship is above friendly (perhaps call it colleagues) then either yourself or the other empire can propose various alliance options (military, economic, social, research).
Military alliances would force the other members to declare war in the event of war and share starbase bonuses/repair/range. It would demand a minimum spend of X% on military. Neither ally could make individual peace treaties or individual war.
Economic alliances would mean a free trade pact. This would give an economic bonus and a freighter bonus (only to that ally). Tax rates and spend rates between the allies would have to be kept within X% (joint economic control).
Social alliances would mean a sharing of social aspects (music, drama, poetry ...). This would give a moral bonus and share influence in unowned sectors. it would cost money to maintain (sponsorship of cultural activities).
Research alliances would give an X% bonus to research. They greatly increase the chance of known technologies being accidently shared with the ally. Research spending must be kept to a minimum x% spending.

Should you have all 4 alliance types with another race then a merger offer can be made. This would join both your empires together, leaving you in control, but you loose all the alliance economic, social and research bonus' (cost of merging, unhappy citizens, etc).

Paul.

It is a treaty event. As far as I know the best status one can get without one side or the other proposing an alliance is "close".

Once "close" status is achieved and if both sides have researched the Alliance tech then "Alliance" becomes an option on the diplomacy screen.

There was a discussion earlier on what the costs associated with breaking an alliance were, the specifics escape me at the moment, but it boiled down to the fact that defaulting on a treaty alliance should have a major downside to it in terms of other races trusting you in the future.

I do like you ideas of the different types of alliance and would like to see the "merger option" become part of the game.
Cheers
Magus

'I personally think that allied status should be a treaty event and not just automatic if your relations are good enough.'

It is a treaty event. It's set up as an automatic occurance right now for testing (and, I'd have to guess, because development efforts are being put towards implimenting of other things for the moment). That will probably change in one of the next few builds.