I been starting to think that quasi-identical relationships are the best. Both people will certainly feel awkward, but with open 2 way communication and acting constructively upon that communication, you will become a better person. This is because you are subconsiously expected to play the role of your conflicting partner.
For example, if you are ENTj, to keep your ENTp partner happy, you have to act like an ISFp. If you are ENTp, to keep your ENTj partner happy, you have to act like an ISFj.
The important elements in the relationship would be the same as for any other relation - for example communication and patience.