Some people are straightforward and true to themselves, some others have multiple personalities and are prone to schizophrenia.
The latter group is more common among women, as they are the ones who often need to adapt in a relationship. They are like time bombs, just waiting for the right time to explode (usually when you don't expect them to).
My greatest failures in life have been with such people, as I didn't properly recognize their nature. So, I find it useful to draw sums, to find a way to spot them out before it is too late. Maybe someone else may contribute to the topic.
So, let's define their traits. They have a heart, but they usually don't listen to it. They have a face/personality for each situation and person. They may have multiple email accounts, one for every scope. If they are into online dating, they are likely to talk to many and telling each of them they are only talking to one. They may be into a relation, but have their profile in some other "unknown" dating site.
They are never straightforward, despite they just claim the opposite. They have a really bad communication, at least about their inner self. They take decisions, sometimes based on revenge or their own pride, but they don't share the reasons. So, their behavior seems ambiguous. When you see something strange that you cannot explain, and you just find telling yourself that you should just accept that because it's not such a big deal, you miss a big underlying issue, which you will never know. If you feel like being driven nuts or that you just got a clod shower, that's not your issue. It is simply because you are confronted by one face, which that person chose to show you. Of course, you could try to reach another face, but those people don't like to be unmasked, so they will never recognize it or allow you something different than they show, even if their underlying feeling may differ. They are not used to be true to themselves.
Obviously, with straightforward people simply communicating may solve issues very quickly. But with multiple personality people it never works. Even if you solve one thing, they will present you with another thing, just changing to another face, or reinforcing their current face. You may notice that they don't use the same face with others, but just with you. They may even talk to others about you in completely different and contradicting ways.
One sign is that, in a relation, they pretend or expect something which is very different from their ordinary past life. It seems that all is due, they dictate you the rules of the relationship, what they expect, how it should be. But it seems never enough. See their past life, and you will notice that nothing like that ever existed. You are not a brother, a mate, you will never be someone of her family. You will be always looked with different eyes and scrutinized for what the whim/expectation of their current face is. Don't try to get to their heart, because they won't allow. You will be just presented with things to do, behavior rules... which lead to nothing and have no genuineness. Love is selfless, not incensing her whims. It will never be love on her side. The only fact that she puts conditions is a defense, a distancing from you, not giving herself to you. She is so busy to maintain all her personalities that it is impossible for her to give herself. Indeed, she doesn't have something she can give, as she is confused herself.
This bears a heavy consequence. Those people end up not knowing themselves. They confuse each personality and don't know what they are. What can they give to their mate? They can only give what is their current personality with them, which is indeed a hidden agenda. She would never call it so, of course, but everything revolves exclusively around pleasing that face of them. So, it is indeed a hidden agenda, as that is not their heart, but a mere facade. The paradox is that the hidden agenda is in front of you; it is her face, which you think is genuine. But the real hidden thing is her heart, which is hidden to her too.
When it comes to become one with their mates, this is impossible, as they cannot be one with themselves either. So, their marriages are doomed to failure.
Other signs of their multiple personalities is when they mix heaven with hell, so to speak. As an example, they always shield behind God. But at the same time they advise about psychology, which is a pseudo-science that labels all humans as "animals" that have to obey to social rules or be exploited. Psychology ruins the life of so many people, exploits child trafficking, feeds the pharma industry. Every few years they invent new "social illnesses" that have no scientific backing, just to exploit people and do their business. If your mate advises to go to a psychologist, better to run away before it is too late.
Then, when a multiple personality person reaches or exhausts her goal/face, she drops you in no time. She really has no problem to do it, as she never had a genuine feeling. Despite the appearance, they are very troubled people. They constantly fight among their multiple personalities. So, they are never happy, always complain of something. They may feel internally very broken. Their suffering heart may push them to seek some exit, because it knows what is genuine. But their personalities will kick in to ruin everything and they will never recognize that.
I have loved people like that. I know their heart probably more then they know it themselves. I cannot withdraw my feelings, because I am straightforward. Like the sun, I shine my feelings. If one decides to shield under a roof or just trashes me to the bin, it's their issue. Of course, I would never go any further, because those troubled and immature souls need a long way to redeem themselves before being fit for any true relation. As used as they are with themselves, they only see the facade in the people near them. They are unable to see the heart, which is just an empty word. I can only wish them to live their empty life without damaging others, and if they have a chance, improve their own being.
I usually spare those people of my comments, as I prefer they are left at least with a remembrance of what a pure feeling is, so that it may be of help in their future. But I recognize it is a sin if I don't tell them, because it doesn't allow them to grow, and we are all here to become better beings. As useless it may be, at least toward me, they may be better with another some time in the future. Maybe a seed will sprout some day. At the end, it is always an act of love.