For everyone, what constitutes a 24/7 relationships differs, like everything else in BDSM. The definition of a 24/7 relationship is simply a relationship where the people involved live with one another on a daily basis. A BDSM 24/7 is easiest if explained as a vanilla live-in relationship, with the added knowledge of who is in charge and the priority of placing that person first and feeling content with the relationship arranged that way. In other words, a power exchange from one partner (at least) to another. Be that exchange a dominant/submissive one or that of a master/slave arrangement, or even just during sexual encounters. In my opinion, if a power exchange exists in the relationship (inside or out of the bedroom) it qualifies under the term BDSM.  

24/7 is something that so many people look at as this big deal. A dream, of perfect harmony at all times, with play taking place frequently if not daily. Reality gets lost in the translation. Now, there is nothing wrong with sitting down and dreaming of the future. Allowing yourself to think of the wonderful experiences you and your partner(s) will share. Or thinking of the happiness and physical satisfaction the relationship will bring to your partner(s) and yourself. Doing this becomes a problem only when it over rides reality and the day to day things get lost.  

When discussing taking a relationship into a 24/7 status, you hardly hear of people talking about money, moods, kids, and the million and one other mundane things which affect daily living. They don't want to burst their own bubbles of the idyllic home life. They focus on kink compatability and the limits or terms of the power exchange. Then, they move in with one another, thinking they've covered all the "important" subjects, only to find themsevles surrounded with reality and beset with problems. Often what happens is, they blame the problems created by this oversite on the BDSM instead of the lack of reality base in the negotiation of the relationship. 

The sub will feel guilty, thinking they did not live up to the expectations of their dominant. Or they may resent the dominant for not upholding his/her end of the bargain. The same feelings can occur for the dominant. Further, the dominant may set more rules (or back off on others) thinking that will fix the problem. Either may feel that they were not truly cut out for the lifestyle, and choose to leave BDSM all together. This is all not true since the sad fact of the matter is, they just did not take into account reality. Not everyone is this way, but enough are that I feel this is an important issue to present to people.  

Lets face it, everyone likes to think their lives will be perfect together. I too, love to think that, but life is not like that. no one is perfect, and no relationship is perfect. To expect perfection, is the quickest way to get yourself hurt. Keep in mind that it is the little things which will do in a relationship. Little things, may not seem important, but they are. Over time, little things add up and become major problems if not taken care of. 

Relationships themselves are hard work. A BDSM relationship is even harder. Specially at the beginning. It takes effort to keep communication open and honest. It takes effort to do a scene, more effort than vanilla sex specially if the people involved prefer an intense or complicated level of play. (tying knots takes time, setting out and applying cuffs takes time..etc.) Often people forget to discuss their daily schedules and stress levels from work. Sure, "leave work at work" sounds great, but it doesn't always happen that way.  A sub who stays at home all day, may forget the stressors that are affecting their dominant are from both the household and his/her work environment.  

Bear in mind that your loved one, does have habits which you may see as cute or endearing now, but 6 months or a year from now may very well drive you crazy. Be prepared to accept the flaws in your partner that are not easily changed or these flaws can become relationship breaking fights. Be honest with each other. Do you snore? Do you have to have your clothing folded in a specific way? Are your canned good alphabetized? Etc. Think of these things and discuss them. Be prepared to compromise on some things. It is up to you to decide what you will compromise on, and what you can not stand compromising on.  

Discuss time constraints, outside stressors, what you know about your moods and how they are affected as well as who handles the bills, splitting responsibility of the children, handling disagreements, and all the same things you would discuss were you planning a pure vanilla marriage. Putting together a 24/7 BDSM relationship takes more effort because not only do you have to discuss the BDSM aspects (power exchange, kink compatability, limits hard or soft ones, rules etc.) but you also have to discuss the mundane things as well. Leave one or the other out, and your relationship is headed for trouble. 

In BDSM, we are fond of telling one another to try to cover "all the bases before playing", keep that in mind when taking a relationship to a live-in 24/7 arrangement, and you will increase your chances of success.