It is believed that if we have cheated someone in the name of love, its is due to the fact that either one would have cheated the other in the previous birth, if not they will get cheated in the next birth. How far is this true
This is TOTALLY UNTRUE. In the matter of reincarnation and karma, Vedas are very clear and provide logical explanations for every situation. There is no room for ambiguity and difference of opinion. Therefore, one will do well to ignore popular belief in this regard. It is essential that one should seek expert opinion as you are doing.
Cheating is cheating and it does not matter whether it is done in the name of love or otherwise. Theory of Karma does not differentiate between the reasons for cheating. The questions is whether someone is hurt because of the cheating or not. If someone is hurt then the person who committed the crime of cheating will face negative consequences in this very birth and it will mostly not carried over to the next birth.
It is very rare to get human body. It is a even more remote possibility that two individual happen to meet each other as human beings in more than one life time. Therefore, the situation described in your question is practically impossible.
Also please note that the punishment for one type of crime need not be that one should become victim of the same type of crime. The punishment is ALWAYS in the form of getting hurt. So if I hurt someone by cheating, I may get hurt by falling down the staircase and breaking my bone. Thus, if someone hurt another by cheating, he or she need not get cheated in return but surely will get hurt.
Thanks for asking this question. If you need more clarifications please post a new question. Thanks.