[@duskshine749] that's a very good question! People may marry outside their suit, but it has some consequences. It can depend on alot of things what happens: House Number plays a part as well, along with corruption in a suit. 

A Heart marrying a Spade would be a relatively appropriate match, a Heart may do this if their family is running out of wealth and the Spade would gain renown from it. For Spades, this is their most covetted match. The family would probably take the Heart's Name/House.

A Heart marrying a Club is more complicated, depending on circumstance. Generally it would be frowned upon, but as Hearts are motivated by... well, their heart, it's not unheard of. Often a young maiden princess will be swept up in the embrace of romance, falling for the Head of her Guard or a bodyguard. While it's not unheard of, it is looked down on, and most hearts would be disuaded from such pursuits. In the example, if the maiden leaves her family she would join the Club family. Or, in the example of a Champion or Knight being promised the hand of a highborn in exchange for a victory or quest, the Knight (in rare circumstance) would join the Heart's family.   

A Heart marrying a Diamond would probably result in the Heart being disowned/banished by their family and lose any sort of protection or benefits from their Suit. The Diamond would not gain any renown, except possibly in one's suit, but Diamond's are often spiritually motivated and don't care for social shenanigans as much, so their House Number might not change at all. In this instance, regardless of whether love was involved or not, the Diamond would have been considered to have somehow enchanted or corrupted the Heart into this action, and if anything, shunned all the more or possibly punished. It's a tragic union.

Now, if we're talking a Corrupted Heart... they could take many Diamonds as partners as a pseudo-harem and, if they so willed, it wouldn't be seen as an 'official' marriage if they also had a Heart partner. Think Game-of-Thrones style or any of that sort of thing that happened in Ancient Times. Not very savory, but it could happen.

Spades marrying Clubs: depending on the House Numbers of each, this could range from being a very good match to a terrible one. Spades might take interest in a unique skillset that a Club family has, or it might be a marriage of convenience for a Spade (House 9 Spade marrying House 2 Clubs, for example, could push them up the rankings) whereas Spade 2 marrying Clubs 10 would be shunned quite severely, [i]particularly[/i] by other Spades, unless the Club family was particularly skilled in some way.

In alot of cases, though, Spades and Clubs can be quite complimentary, particularly the more "rogue" style Spades who are all about secrets, sneaking around and being nimble. In some cases Spades and Clubs who have fought together in a Deck will marry after they have put adventuring behind them.

Spades and Diamonds... No Spade in their right mind would do this. [i]Unless[/i] the Diamond is a particularly strong one with unique magic the Spade is fascinated with... but rarely would that be grounds enough to marry them. A Spade marrying a diamond, even a low spade to a high diamond, would be a match in a million, perhaps only brought on by a shared love of magic. Diamonds are basically a forbidden match to high borns, for the most part.

Clubs and Diamonds... Appropriate, though the Club basically forfeits any expectation to rise in the House Number ranks. They'd have to work twice as hard to make any headway. 

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There's lots of different options depending on a lot of things, hopefully that'll give a pseudo-overview :D but if you want help with a specific situation, I am available to help brainstorm what that pairing might be like~