If you have watched Mass Effect 3 and have not been entirely convinced by its ending, perhaps you could take a look at this “brief” explanatory video of the game, which could have more ins and outs than it appears at first glance.
It’s not clear to me that Bioware has been so convoluted, but the truth is that the fans who made the video have done a pretty fine job, although they acknowledge that they still have unknowns to solve. Sadly, it is most likely that the end of the game simply responded to a change of scriptwriter and the pressure to release it as soon as possible.