Sim changing traits through gameplay (Growing Together)

While I still wish the game offered more traits to choose from, I have to say I do enjoy this new feature. So far it has happened for three different Sims I am playing and the suggested new trait always made sense in context. I didn't accept all of them but I especially enjoyed when one of my Sims - who has been in a relationship for a long time - was offered the 'loyal' trait. That's exactly how this trait makes the most sense imho. The Sim now has 4 traits, btw. I wonder if you can play a Sim with the 'non-committal' trait in such a way that the game suggests replacing it with 'loyal'. Or vice versa.