You two may go through some rough times together, not necessarily because of clashing personalities or other difficulties within your relationship, but more due to outside circumstances that are beyond your control. You could run into money troubles, for example; sometimes it might even seem as if the world is working against you, especially if big problems occur. You might make an investment together, for example, that doesn't turn out, despite your best efforts and intentions.
But even if these kinds of things happen to you as a couple, it will be very important not to give in to that kind of pessimistic thinking -- that the world is against you and there's nothing you can do about it. In fact, you'll find that despite the issues you'll run into together, you'll develop plenty of strength to deal with it. You'll be remarkably resilient as a couple, especially if other influences between you point to a supportive, teamwork-oriented connection. It may well end up that the problems you face together will strengthen your bond and make you a stronger, better-functioning couple overall.