Quarrelling, pressure, different habits, taking control and no freedom are five major problems of living together. There are a number of major differences before and after marriage:

Before marriagedddddddddddddddddddddd After marriage
1. Have our own home and bedroom. dddddddd1. Sharing the same home and bedroom.
2. Sleeping alone.ddddddddddddddddddddddd 2. Sleeping together.
3. Seeing occasionally.ddddddddddddddddddd 3. Seeing every day and night.
4. With privacy. dddddddddddddddddddddddd4. Without privacy.
5. Hide our bad habits and demerit.dddddddddd5. Showing our bad habits and demerit.
6. Have our own secrets. ddddddddddddddddd6. Sharing all the secrets.
7. Financial independence. dddddddddddddddd7. Financial dependence.
8. Responsible for yourself only. ddddddddddd8. Sharing duties and responsibilities.
9. Free as a bird. ddddddddddddddddddddddd9. Locked in a cage together by marriage.
10. Ethically allowed dating other guys. dddddd10. Ethically not allowed dating other guys.
11. A little prince or princess at home. ddddddd11. Trying to be the emperor to take control of dddddddddddddddddddddddddddddddddddddddeverything.
12. Have place to hide when you are upset.dddd12. No place to hide when you are upset.
13. Take care of your own self. dddddddddddd13. Take care of your own self and another person.
14. Do whatever you like. dddddddddddddddd14. Can't do whatever you like.
15. Quarrel often. dddddddddddddddddddddd15. Quarrel a lot more often.
16. Love each other. dddddddddddddddddddd16. Start despising each other.
17. Think he or she is the right one. ddddddddd17. Think he or she is the wrong one.
18. Think you understand him or her dddddddd18. Aware that you don't know
dddthoroughly. dddddddddddddddddddddddddddhim or her at all.
19. Happiest of all. ddddddddddddddddddddd19. Completely heart-broken.
20. Full of confidence. dddddddddddddddddd20. Lose all your confidence.
21. Have temper. dddddddddddddddddddddd21. Have a worst temper.
22. Praising each other. ddddddddddddddddd22. Criticizing each other.

Another big difference before and after marriage is, we can go back to our own home after quarreling, maybe we won't talk to each other for a few days or weeks, but we will start missing each other, and start introspecting our attitude and what we have done wrong. After we both cool down, one side can not endure the loneliness and concern then holds out the olive branch, and both sides will soon be friendly again.
If we are living together, we will be staying in the same home after quarreling, with a lot of direct eye and body contact. If both of you are as stubborn as a mule, both trying to win your points and battle, the argument will go on forever. Even if one side leaves for the night and comes back the next morning, when either side begins a conversation, very soon both of you will move back to the war zone, and start arguing about the same things again and again. Or you will hear a lot of banging door, throwing stuff, staying out late, yelling or not responding to each other. This kind of behavior may go on for a few days to a few months. If both sides don't stop adding fuel to the fire, hate, anger, annoy and pressure will build up, your love and relationship will gradually go downhill.
Different habits and lifestyle are also irritating to us. Couples always argue between cleanliness and impurity, tidiness and disorder, silence and noise, and casual and formality. Habits and personality are have been build up or establish for many years during our life span, the autonomy and egotism in our human nature will make habits and personality very hard for anyone to alter.
A lot of couples also have problems in command or taking command. With the rise of the feminism, both sides want to take control in decision making, family leading, finance and thought of the other half. Both sides want to apply their own rules to the other half, assigning what one can do and what one can't do. If both sides can not smoothly coordinate on the above issues or either or both sides always attacks their agreement, then blames or arguments will be on forever. Pressure and dislikes will build up until one-side moves out to escape the difficulties and troubles, until then, both sides will have a chance to cool down.
Telling tales is another problem we are facing everyday. When we are not happy with our love one, we like to talk to someone for advice or to be consoled. Sometimes a caring but careless friend will try to act as a mediator, but could be adding oil to the flame and get you into more blame and dispute. Because nobody likes their family difficulties to be spread around, to be announced to the whole world, and have everyone coming to him or her for mediation, after hearing those one-side biased complaints.
We should be carefully handling these kinds of complaints, and shouldn't take them at face value. Usually both sides will have their own stories; it will be pretty hard for an outsider to judge correctly the rights or wrongs of both sides. Especially some people like to exaggerate the whole case, to set everything in favor of them.
Some people have a big mouth; they can not keep others secrets, and like to spread them widely around. They are wolves in sheep's clothing that loves to sow dissension. They will act as your good friends, to tell you others secrets for your own good, but their true intention is trying to drive a wedge between you two, and to make you two hate each other.
Winning you points or argument will not help your marriage, bias and extreme rules can not help your relationship, confining his or her freedom may build up pressure, and asking for improper advise may lead to more dispute. Getting married means we are entering another stage of life, we need to be mature, forget the past and learn the philosophy of living together with less freedom, more responsibilities and start taking good care of others.