Sometimes you can opt to attack a ship you’ve approached, but I don’t think I’ve ever been able to talk my way out of being attacked. Nearly all of the quests are solved by traveling to a location, checking it out (maybe blowing something up), and returning to the questgiver.

There are definitely a few points where you can choose to accept or decline an offer from an alien, and what you choose may have consequences that must be resolved through a sidequest, but there’s never a risk of endangering an alliance by insulting your allies or anything like that. “Funny as they often are, it’s very rare that the dialogue decisions you make seem to have any effect on the outcome of an encounter other than to play your character straight or as a wise-cracking captain with a mean streak.