Venus opposite Saturn means that your fear of unworthiness causes you to be attracted to people who will prove that to you ... by rejecting you.
And/or that it causes you to subconsciously mess up your relationships, causing them to fail and proving to your subconscious that you are not worthy.
You CAN change this subconscious attitude. That is what cognitive-behavioral psychology is about.
And our birthchart only indicates how we will be IF we do nothing TO change. So you are not doomed.
Venus square Mars means that what you want out of relationships contradicts how you go about pursuing relationships.
And Mars square Saturn (which I am assuming is also happening) means you take action when the situation calls for patience, and you hold back when the situation calls for action .. so that it is hard to achieve what you want. Until you learn to have better awareness and timing.
If Mars IS square to both Venus and Saturn, this is T-square configuration, meaning that all the tension and inner conflict of the Venus-Saturn opposition funnels into the square planet: Mars (called the Focal planet of the T-square). Meaning that you over do your impulsiveness and change direction too often to achieve what you want.
An astrologer could explore this with you for over half an hour. It would be done in a two-way conversation, each side putting in their knowledge (the astrologer knows the theory, but YOU know how YOU respond to the influences in your birthchart) It is a complex set of aspects.