There does not appear to be a visa requirement to go there to marry, such as a "fiance" visa since you do not have any plan to remain there long term.
These are the only type of Romanian visas:
Types of visas granted and issued by Romania:
1. The airport transit visa (A-type): it allows the access of aliens into the international area of an airport until their access is allowed on board of the plane towards the country of destination;
2. The transit visa (B-type): it allows the transit of aliens through the territory of Romania, for a period of up to 5 days;
3. The short-stay visa (C-type): it allows the entry and the short-term stay on the territory of Romania for a period of up to 90 days within an interval of maximum 180 days from the date of entry (in the case of a multiple-entry visa, the period of residence will be taken into account starting with the date of the first entry and the duration of stay will be the sum of the individual stays in this period). The Romanian short-stay visa is granted for the following purposes: for an official government mission (C/M), for tourism (C/TU), business (C/A), private visit (C/VV), transportation (C/TR), sports activities (C/SP), as well as cultural, scientific, humanitarian or other purposes (C/ZA). The period of stay cannot be extended under no circumstances.
4. The long-stay visa (D-type): it allows the entry and the residence on the territory of Romania, for a period of maximum 90 days (maximum validitz is also 180 days), for the following purposes: diplomatic and mission assignment (D/DS), economic activities (D/AE), professional activities (D/AP), commercial activities, such as investments (D/AC), religious activities (D/AR), work (D/AM), studying (D/SD), family reunification (D/VF), temporary work assignment (D/DT), research (D/CS), as well as other puposes (D/AS). In this case, the residence can be extended at request over the 90 days, by the issuance of a temporary residence permit. The application for the residence permit has to be filed with the Romanian Immigration Office, at least 30 days before their right to reside in Romania granted by the visa expires. Failing to do so, the visa will be canceled and its holder has to leave Romania.
Since laws can change without notice you should contact the Chancery prior to your making final travel plans
Chancery of the Embassy
Address: 1607 23rd Street, NW, Washington, DC 20008
Phone: +1(###) ###-#### +1(###) ###-####/p>