Regarding bipolar in the Manic phase, or hypomanic phase, or on meth (which induces a manic like state), I do have some insight. I'm a medical person, and I do a lot of this type of work for a living.
Cognitive stuff gets screwed up, thoughts go from random thoughts (like "I'd like to fuck her") to words/actions ("wanna fuck"/random unsolicited touching) which if responded to become actions.
This is important to know, particularly if you are dealing with bipolar disease and addictions, it is like the regulator on the brain malfunctions and there is no inhibition of action.
This can also happen with illegal drugs, alcohol, and with prescription drugs that are used properly as well as abused (antidepressants, anxiety medication, sleeping medications, sedative/hypnotics).
As mentioned above, a thought becomes a word and then an action. The only thing that is missing in most cases of "misconduct" is the receptive responder.
So a deliberate serial philanderer may approach 20 men/women before he/she gets a response from a single susceptible usually non-responding person but one who is now in crisis, or from another serial cheat.
On the other side of this, for a usually faithful person, or a "non-serial philanderer", who is on drugs, having a medical problem, or having mental health issues (like a manic episode), who is now having regulation problems with their inhibitions, if they are approached by the other person (whether that person has the same problem as they do and it is a temporary problem or if they are just a serial philanderer) they may NOT BE ABLE to stop their response. Their inhibitions are deregulated and don't kick in, and they become like a car with a stuck accelerator and failed brakes.
These people are extremely susceptible to suggestion, of any type, from any person, perceived or actual.
Not making excuses, but this actually happens. This is why we are not allowed to have sexual relationships with our patients, despite many people in the profession who argue (privately) that we should be allowed to do this, and the lesser number who actually do engage in sexual activity with patients.
I have seen this in patients first hand, and in those who are being treated for depression and other disorders, and in those with cognitive impairment due to various diseases (Huntington's Disease is one well know for this as is Bipolar Disorder, but strikingly enough we also see this in patients being treated for Parkinson's Disease and we use the same drugs for treatment of Restless Legs Syndrome and Periodic Limb Movement Disorder, and in those patients who develop Alzheimer's and Lewy-Body Dementia occasionally).
Just for clarity, these patients are "not themselves" when this happens. They are functioning in an aberrant cognitive state. The damage they do is no less, but it is something the person/spouse/counselor/family/friends has to keep in mind when they are evaluating the "origins of the behavior".
Unfortunately, some who fall to this type of problem are never able to deal with what they have done when they come "back to themselves" and suicide is very high risk as well as drug use and other dysfunctional behaviors in order to "try to forget" what has happened.
I have seen this professionally, and unfortunately, I saw it personally in my own family when my wife was treated for depression. Talk about an education.
NOTE: Edited to remove misspellings and finish the post, it double posted from a handheld device, before I was done writing it. Sorry for any confusion.
[This message edited by standinghere at 1:56 AM, March 19th (Monday)]