An enormous amount of idealism will make this relationship a tricky maze to navigate. You'll be busy projecting memories of a lover from long, long ago -- lifetimes ago -- which exist now only in the ether of your mind. But still these images will persist, superimposing themselves over this person as they truly are today, making it nearly impossible for you to see them in their true light.
At the same time, they'll be busy doing nearly the same thing to you, idealizing you based on those same past-life memories that are submerged in their subconscious mind, looking to you for emotional clarity and validation that you may not be able to provide. How to fight through all this projection and illusion? Clear communication will be an absolute must, and the burden of communication will likely be mostly on your shoulders. Take extra special care not to be dishonest with your lover, because even the smallest of white lies can be misconstrued here and turn into something more damaging. If you do pursue this connection, make sure that you take this idealism and projection as a lesson, by being aware of its power and doing everything you can to work against it.