All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger. We ask Allaah to exalt his mention as well as that of his family and all his companions.
First of all, it should be noted that it is very rare for marital life to be free from problems, therefore, it is wise to act carefully and not hasten things as this may lead to making the situation more difficult and the solution hard to achieve. However, if it is confirmed that this man has deserted his wife all this long period without a sound reason, then he is very wrong.
As regards his wife, she should not hasten to ask for divorce until she finds out how sincere he is in taking her back. In this case, she may seek the help of some righteous people who would arbitrate between her and him. Then, if it is confirmed that he is truthful in taking her back and she most predominantly thinks that he will not harm her, then it is more appropriate for her to reconcile with him as reconciliation is better. However, if she fears that he will harm her, it is permissible for her to ask for divorce. If he accepts, then all perfect praise be to Allaah, otherwise she may take the matter to an Islamic centre in the country where she resides so that they would study the matter and get a divorce for her even by her renouncing the remaining of her dowry or other debts due on him. For more benefit, please refer to Fataawa 89039, 85034 and 84309.
To conclude, this woman has the right in her dowry and the debts which her husband owes her, and he is obliged to repay her whether or not she reconciles with him.
Allaah Knows best.