Not just in Qatar, in many Asian countries, people are really hospitable and love to insist on giving more and more food to the guest. The guest is expected to eat and drink what is offered. Obviously, you can not do that always. The easiest way out of such a problem is to just say, "I really do not feel like having coffee, can I please have some water?" When you request somethting yourself, the host is obviously certain that you are not refusing food out of some hostility but it is just that you really do not want it. You do not have to drink the whole glass, just half of it would do. And never forget to compliment the host on the offering by saying things like, "nice, the water of just cold enough, nice coffee, I liked the sweets alot."
Not just in Qatar, in many Asian countries, people are really hospitable and love to insist on giving more and more food to the guest. The guest is expected to eat and drink what is offered. Obviously, you can not do that always. The easiest way out of such a problem is to just say, "I really do not feel like having coffee, can I please have some water?" When you request somethting yourself, the host is obviously certain that you are not refusing food out of some hostility but it is just that you really do not want it. You do not have to drink the whole glass, just half of it would do. And never forget to compliment the host on the offering by saying things like, "nice, the water of just cold enough, nice coffee, I liked the sweets alot."