Here's a way to get that Settlers of Catan feel but in a form playable with two players. The Rivals for Catan is a revamp (and improvement) of the Catan Card Game, maintaining the gameplay but removing some of the frustrations and adding a few new elements. Players still roll dice to gather resources, but action cards are now easier to play and less brutal.
Components: 2 large wooden dice (event and production), 2 wooden tokens (trade and strength), and 180 square cards (including starting layouts for both players, settlements, roads, cities, resource regions, event cards, building and action cards, and 3 different theme decks). The dice are very nice, and while square cards may frustratingly always seem in the wrong direction, the resource region mechanic makes the square cards very useful.
Each player gets a starting layout with two settlements connected by a road, and six resource regions on the corners of the settlements, one for each resource type and die number. You start with a hand of three cards.
On your turn, you roll the dice. First, the event die happens, which may flip an event card or otherwise effect your resources. Then, the production die happens, and you produce one resource on each field matching that number.
After production, you may play action cards from your hand and build things. Some action cards -- especially the nastier ones -- have pre-requisites that prevent you from playing them too early in the game.
Settlements, roads, and cities are in the center and can be built by either player. A road must be built for each additional settlement you build. New settlements come into play with two new resource regions, increasing your production. And cities give you an extra point and allow the creation of special city-only buildings.
Players may also build cards from their hand, ranging from expensive city additions for extra points, to inexpensive trade fleets that allow better resource conversion rates, to vikings that give you a strength advantage over the other player to gain event benefits.
At the end of your turn, you draw your hand back up to three cards, and then may discard one card from your hand to replace it with a new one from the same color deck.
The first player to achieve 12 victory points wins.
NOTE: This is only a brief summary, with many details omitted.
The Good And Bad
Rivals for Catan is a great game for couples, keeping the dice-rolling production, the conversion of resources, and much of the same feel of Settlers of Catan but playable with two. Setup doesn't take too long, and open-ended trading has been removed, making it a slightly faster alternative.
Rivals has been well-balanced to make it unlikely for one player to fall frustratingly too far behind. You get at least one resource on every die roll, even if it's not the one you want. The attack cards have pre-requisites, and even then, have been toned down from the original Catan Card Game so as not to destroy a player's best building with no recourse. There are even some clever new buildings, like the Marketplace, which give you a free resource on any roll where your opponent would produce on more regions than you. In short, the game has been re-balanced to have less direct conflict and prevent runaway leaders.
Rivals comes with three themed decks of cards, each of which has a very definite feel. The Era of Gold game is focused on trade and production, perfect for those who want a "friendly" game. The Era of Turmoil, conversely, is filled with attack cards, and events that punish players based on who has more strength. The ability to choose which deck to use in any given game (or all three) is a very nice perk.
Building stuff is fun. This may seem obvious to some, but there is something inherently compelling about gathering resources and using them to slowly expand your empire and grow your gathering and expending powers.
Luck plays a non-trivial role in this game, and some may be frustrated with repeated die rolls that help your opponent and not you, or a handful of unplayable cards while your opponents draw tons of helpful actions. Things may tend to even out over the course of a game, but it sure feels unfair when your hand is useless cards and your opponent keeps getting free resources.
If you are so foolish as to fill your hand with cards from the theme stack, you can never draw a regular card again until you manage to successfully play one of the cards in your hand. The obvious solution is "Don't do that", but it still seems unpleasant.
In the expert variant with all three theme decks included, most cards in the theme decks rely on a card of which there is only one copy. Whichever player manages to build one of these buildings makes many of the cards in that deck useless for the other player, which seems odd given how balanced the rest of the game has been made.
Some may feel that the game has become too balanced, and dislike the lack of ability to open up a lead on your opponent and smash them mercilessly.
Conclusion: Rivals for Catan is a solid 2-player game. A longer playtime than you might expect from the small box, but a nice mix of luck and strategy, and plenty of balance to make it a good "couples" game.