First of all we have to be very clear here that character cannot be seen in a birth chart. Birth chart is like a map of our life, our perspective on life, things, people, relationships. If person will act on bad birth chart aspects, it all depends on how evolved this person is, how increased is his consciousness, awareness and spirituality. What we do with our birth chart, how we evolve or no, it is completely up to us and our free will, no matter how good or bad your birth chart is.
Birth chart is really the map of that person, it is that person´s perspective of the world.
But what we can tell and see are predispositions and inclinations of that person.
There is plenty of combination here, so I might forget something here in this article. My intention here is to give you sort of flavour how to read it and what are important markers here.
First, lets talk about houses in a birth chart. In my opinion, when it comes to cheating or being unfaithful in a relationship, there are always somehow included houses 5th, 8th and 12th. Some of you might be surprised, why 5th house, as it is originally Leo house and Leo is such a loyal and stable sign. Truth is that 5th house is also house of romances, our first loves, first dates, but not long committed relationships. If you just date someone, it can be seen here. Typical example are our first loves, they are found in the 5th house.
8th and 12th house are both water houses but very different in its core. However, one thing that they have in common is that they both represent secrets, things that are hidden, our experiences that are buried underground, situations that cannot be touched or seen by other people. Very much behind the scenes acting.
So, if there are any personal planets, such as Mars, Venus, Moon in these houses receiving bad aspects from other planets, it is worth dig deeper here.
For instance, Mars in the 5th , in hard aspect to some other planets, such as Uranus, Pluto, Neptune, Venus, Moon, (especially if 8th or 12th is involved, like mars in 5th squares moon in 8th, or mars in 5th squares venus in 11th, but venus rules 8th house). This person very naturally likes hook ups, one night stands, he is very easily seduced or dragged into this behavior. These activities – extramarital affairs don´t mean a lot to him.. it is actually some sort of release, fun for this person.
Venus in the 12th house or Moon in the 12th house loves their privacy in a love life. What this really means, will again depends on the aspects that Venus or Moon receives. If these planets are in weak signs or somehow damaged, we that can predict that there is this inclination towards affairs.
Another example would be Venus square/opposition Neptune – illusions and dellusions in love. This person falls in love easily, fantasizes, and this happens a lot, even this person is in committed relationship, still inclines to fall in love with someone else. Falling in love on a platonic base might be enough for him, but sometimes he acts on it and is having an affair. These people are prone to affairs and choose unavailable men, women in a first place!
Mars in hard aspect to Neptune is also another example of behavior in a sexual area which can be full of deceptions and lies.
All above also applies if planet which is involved rules that house, not necesarilly has to sit there.
Lastly, you should also remember one important astrological rule: if you find one indicator, it means really nothing and we cannot tell a lot just by one thing. If you find two or more indicators in a birth chart, I would be very alert with that person.