In Mass Effect 3, you can have a relationship with Miranda again just like in Mass Effect 2, however there is a catch.
The only way to romance Miranda in Mass Effect 2 is to continue the relationship from Mass Effect 2.
Hopefully you didn’t break up with her by the end of Mass Effect 2, because if you did then unfortunately you’re out of luck.
Lucky for you though, there are some new romance options for you to check out.