In his relationship with Grace, Mali wants to have the best of both worlds. On the one hand, he wants a Western girlfriend that he can show off as a trophy. On the other, he wants someone who will adopt the domestic role of a traditional Indian housewife and cater to his every whim.
One gets the distinct impression, then, that Mali is using Grace for his own ends. The inherently exploitative nature of this relationship can be seen in the fact that Mali hasn't deigned to marry Grace, which his father Jagan finds totally shocking. Mali's evident lack of commitment to this relationship indicates once more that he sees Grace as simply a means to an end, as someone who can be manipulated into asking his father to send him money for his hare-brained business ventures.
Grace seems unaware of Mali's true intentions, or at least indifferent towards them. She makes strenuous efforts to adapt to Indian culture, an indication perhaps that she takes the relationship a lot more seriously than Mali, who spends a lot of time away from home getting drunk.