What MaMU did was nothing close to date rape. It wasn't consensual, yes, but the drug did not force her to fall in love with MU. In fact, MU was taken aback when Soleil revealed that she fell in love with the female version of him, meaning that that was not his intention when he gave her the potion. All he wanted to do is help her overcome her tendency to pass out, which could have proven fatal if it happened on the battlefield.