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.
If this man had conducted an Islamic marriage contract with this girl but he did not consummate the marriage with her and he was not in Khalwah (complete seclusion) with her during which he could have had sexual intercourse with her, then if he divorces her, she is entitled to half of the named Mahr (dowry) unless either the husband or wife gives up his half to the other.
If they had not specified the Mahr, then she is entitled to a gift of compensation (Nafaqat Mut'ah) which will be estimated by an Islamic judge or whoever can act on his behalf according to the financial ability of the husband.
However, if he consummated the marriage with her or was in complete seclusion with her, then she is entitled to the full named Mahr, or the Mahr of the women of the same social status like her if no Mahr was specified for her. For more benefit, please refer to Fatwa 88409.
The husband has the right to refrain from divorcing her until she renounces part of the Mahr or all of it as underlined in Fatwa 89039.
As regards the gifts that are not part of the Mahr and the expenses that the husband or his family had spent on her, as well as the fees paid for her entry visa, then he has no right to take back any of them; for more benefit, please refer to Fatwa 226273.
Allaah Knows best.