Any marriage is hard, but many interracial relationships are more thought out than others (if the couple are responsible adults)as nothing is assumed. I think this is healthy as all expectations are laid out before the deal is done. The discussions of kids, roles, responsibilities, family etc. are essential. If you have enough love and committment to each other you can make the marriage work. Granted the agreed terms and what actually happens can sometimes be much different this can also be said of same culture/religion marriages.

Any lasting relationships take a great deal of work, not just marriage.

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"Diplomacy is the art of saying 'Nice doggie' until you can find a rock - Will Rogers"