Heed Avisg's advice on this, switching drug of choice from one addictive substance to another just delays the inevitable. Best to just do it right the first time.
Best to do a quick taper from Tramadol and perhaps you can hold the Trams for your Fiance and dole them out to him per a taper plan.
Tramadol withdrawal isn't fun, but many here can attest to the fact that it can be done and have many great success stories and ideas to share. Perhaps your fiance could read their stories from this forum and be encouraged by the success's shared. I too had tapered from Tramadol and know how important support from others (and NA) can be and may not had been to get clean without it.
Best Wishes
-Vic
If I were him I would do I quck 21 day taper and get off of the sub If he stays on it to long it will be like switching DOCS. If you look in the health pages I think there is a 21 day tape plan take a look at that . I have been clean fro tram for all most 11 months now you can do it .