@RitaMary no only marriages are saved if you decide to move a couple into a new load or save them only the marriage is saved and it loads new at about 60% romance and 45% friendship. If they're dating and live together they will be saved as typical roommates no romance meter will load in. I've also noticed that the relationship between two sims in one load isn't exactly the same in another load.
They may be very talkative and gain sentiments easily in one load and then be indifferent towards each other in another load