Yes, when running from a relationship the leaver can go through euphoria but normally it does not last long. MLCers and their escaping, rush providing, tactics, manage to make it last more years than some marriages.
My cousin, before he hit rock bottom, has been diagnosed OCD, histrionic, psychotic, borderline and bipolar. He spend a couple of years jumping from psychiatrist to psychiatrist and from psychologist to psychologist. Only the bipolar medication (lamotrigine, that is also used to epilepsy and is a medicine psychiatrists took from neurologist) combined with zoloft plus a high dosage of alprazolan worked. He gradually dropped the zoloft and the alprazolan, had kept the lamotrigine for a little longer. He has been without it for a few months and is again oscilating. His anxiety levels are hitting the roof, one day he is fine the next he is angry and enervated. Think he will have to go back to lamotrigine and alprazolan soon.
After rock bottom, when he “waked up”, at first he was fine and balanced. Soon the frantic begin and he was buying tons of expensive unneeded stuff, changing everything in his home from linen to glasses. He was also being very aggressive with everyone. He had to be taken to hospital again (he was still taking all the meds). My cousin was a wallower, he had “wake up” a years and a few days ago and, so far, it remains a rollercoaster. Especially to his live-in girlfriend and her parents (they live near each other and often dine together). They spend vacations together and my cousin has been showing signs of excess in everything, from food to verbally abusing people.
He and his girlfriend had not had a sex life for years so I doubt most of our MLCers are capable of a regular, healthy intimate relationship with their OM/OW. Maybe in the beginning, from then on, as they become more erratic and instable I think that side of the relationship decrease abruptly, may even end.
As for my husband, when I was still around he was totally bipolar and was not taking any meds. It has been years I'm not close eneough to him to know if is on meds but, even on the distance I notice he oscilates a lot.
Sometimes good things fall apart so better things can fall together. (Marilyn Monroe)