It is absolutely grammatically correct! I think a native speaker would be more likely to say, "Sorry, I can't leave right now because I have a (guest/visitor/friend) here." You might also say, "I can't go (or come) right now." If you actually have a choice, you might say, "I really shouldn't leave right now." In my part of the United States, we want to let the person know we appreciate the offer, so we often apologize (I'm sorry!).

yes, correct spelling and use of the words. you could also say 'I shouldn't leave while entertaining guests in our home' if. hope this helps.