Triss and Natalie ended up spending a lot of time together. Even after their meal and others joined, they continued to converse about things. Mostly about Natalie's crush on Noah. Natalie took what Bee had told her and considered it while taking Triss' advice. She was her person, but she wasn't used to relationships. She never got romantically involved with anyone, so Noah was a first for her.
The problem was that Noah had a girlfriend and was in a relationship with Alice. At least it was a problem for someone who wanted to be with him. Logically, it should not have been a problem. The real problem was that Natalie wanted someone who was taken, and even if she had waited for Noah, that chance might have never come. Triss tried to explain that Natalie needed to move on and not pursue Noah. Even if he broke up with Alice later, that did not mean it was her chance to go for it.