The instance where any wrongdoing is made in a relationship can only be pardoned, is when the wrongdoer attempts to apologize for the blunder. The most appropriate way to do this is by writing an apology letter. This letter should be able to portray the exact emotion that will leave the recipient feeling better and in a position where they are compelled to forgive.
The only way you can achieve this kind of result is if you steer clear from romantic rhetoric and state the reason as truly and kindly as possible and also seek pardon for your ills. The only way your partner can buy into your story is to express the remorse that you feel and similarly assure them on your plan to avoid having the same issues crop up again. The option to seek for forgiveness and request for a restoration of confidence will be met with optimism if you remember to keep it short, simple and loaded with concern. Your bold attempt to reconnect broken ties will be welcomed with open hands if you come out as sincere.