I recently did a just-because experiment and found out that if teens who are bf/gf become step-siblings they will still be bf/gf but won't have the romantic interactions. I guess it works the same way as teens who grow up into YA and their bf/gf are still teens. I don't know if people already knew that (and now that I think about it seems kinda obvious
) but the thought popped into my head and I just HAD to find out, lol.