What do you do?

Suppose you are with your friends and enjoying and your partner i.e either your boyfriend or girlfriend calls you and asks you to meet him or her
and you are not at all interested to leave the enjoyment then what excuse do you give .

Now, I am the third year student in Vietnam National University. In the future, I want to become a good teacher. I like teaching children so much :X

I think it depends on the situation. If it's an emergency and your partner badly needs you, then go to him. But if he's just asking you to leave the party to simply go with him, that would be selfish on his part. You can actually invite him to come over or ask him kindly that you can catch up with him because you can't just leave the party.

if there is any serious matter then i can go with him if simply i never go for a while it depends upon situation...

If it's an urgent kind of call, then you should meet him/her. But if it's just calling to come hang out, then you tell them politely "Tonight I'm hanging out with some friends but I'd love to hang out with you ___" This happens to my boyfriend and I all the time. We usually see each other during the day every day and then in the evening he goes to work at a restaurant. He'll only get a few days off a week and sometimes he'll spend those nights with me or he'll say hey I have plans for (whatever day) but if you wanna do something the next night I have off I'd love to.

It's important to keep your friends and not get totally consumed with each other. You need to try and balance it out by spending time with your friends every once in a while as well.