It is so easy to fall in love with the idea that you are in love all over again when your ex reappears, when the reality is that you may simply be lonely.
Leaving a relationship is a sign that something was wrong or went wrong, and this is something you should keep at the back of your mind when you're considering getting back together with an ex.
It is difficult to forget past problems (lying, cheating, etc) and these will plague the relationship if they are not properly dealt with. If it is that both parties really desire to rekindle their love and rebuild their relationship, they must have the “hard' talks and decide to move forward. If issues are not dealt with and are swept under the carpet, eventually the relationship will fail again.
It is not an easy task to throw your heart fully back into a relationship that previously collapsed. In fact, it is extremely hard and because of this, issues of fear and doubt will linger. Trust goes hand in hand with love, and if you love and trust someone, that is a great place to build a lifetime partnership. But trust once broken is almost impossible to rebuild. If both parties decide to be honest with each other about each other, it is also a great place to restart and rebuild.
It is impossible to forget memories, especially bad ones. These can trigger arguments and can send the relationship you are trying to rebuild on a path of failure.
Many people have tried and have mended their broken love, and many have tried and realised that they made a huge mistake. Reality is, some bridges are best left burnt and some are worth returning to. However, ensure that any relationship you get into will be fulfilling for you, otherwise, you are wasting your time.