Could part of the problem here be that we are people of different generations playing this game? I personally am a bit old - probably older than most of you. And my view on relationships is admittedly a bit old fashioned and not in line with the modern youthful approach. I really don't like the approach that Bioware takes to romantic relationships in this game and find them rather distasteful, but that is possibly just because I am an old fuddy-duddy.
In other words, Bioware has made an attempt to cater for people of different sexualities but has made no attempt to cater to people of different generations or simply those with a different psychological approach to relationships. This is nothing to do with demisexuality per se, but is perhaps linked in our reaction to the relationships. Personally, I don't expect to be catered to - I innately regard video games as a young person's thing, so I am not surprised if there are aspects that I don't relate to. The relationships are one such aspect, so I just don't participate in game.
[I will put this last comment as an aside, since it is a bit off topic, but in my opinion related. As I have mentioned before in a different thread, I was appalled that my inquisitor engaged in sexual activity without my consent. We went from having a nice chat to full out sex without any opportunity to object. However, in hindsight, maybe my negative reaction to this (I had to reload and break off the relationship) was also a generational thing.]