definitely! I am a sunni girl and my fiance is shi'a. mA we r both very happy and will be married in abt 2 yrs iA :).
It works if u r willing to MAKE it work.
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its NOT that simple...i wish the best for u though. once u've children and get a bit older in life and tend to become more religious then the friction in fiqahii masaa'il creeps in big time unless one is NOT religious at all. in that case, it doesn't matter if ur spouse is sunni, shia, christian, jew, or any other for that matter. i wud stay away myself if i were to consider marrying some1 from a different sect or religion.**