While I could make a case that dina d’malchusa applies here, at least according to the Rema, I don’t have to. Just saw that SA Even Haezer 50 states this: ????? ??????? ???? ????, ??? ?????? ???? ??????, ??? ???? ?? ????? ?????? ??? ??? ???, ??? ??? ??? ??? ???? ???, ?? ???? ?? ????, ????? ???????? ???? ??? ?????? ??????. (?) ?] ??? ???? ??? ???? ?????? ???? ?? ?????? ?? ???? ????, ?? ?????? ??? ???? ?? ????, ???? ???????; ??? ?? ??? ??????, ???? ???
To put it simply, all gifts (except for food and drink) have to be returned. I wonder what the sevara is behind this halacha- is this what the American concept of ‘in contemplation of marriage’ is grounded in?