I think the end game questions/discussion for this show is really difficult... Because you never know what anybody hides and how bad it will be. We don't even know who Liz is now, maybe it depends on who she is who in the end will be the perfect guy for her.
I wouldn't go as far as to call any of the two couplings end game yet
Both had their moments and both had their bad times.
But yes, there's potential for Ressler and Liz. I think nobody can deny that.