Right now+must: You must be enjoying it right now...

[Tom]

Dear Alan

I am grateful to you for your teaching. Still there is some confusion.

You must be enjoying it right now,--------------?

Which question tag to be used? aren't you OR mustn't you? Because the sentence is more inclined towords present continuous tense, not the obligation of enjoying something.
Secondly, you did not tell if don't you is wrong in the given sentence or just a matter of preferance.

You look at her this way. You must love her,-------------?

mustn't you and don't you

Because again the sentence is inclined towards present indifinate tense rather than obligation.

With many thanks

Tom

[Alan]

Hi Tom,

Must doesn't always mean obligation. It also ,as in your examples, suggests, it's a fact.

In your sentence:

[Yankee]

Hi Tom

Even though you directed your question at Alan, and Alan has also already given you some good input, I'll give you a little input, too. My interpretation is a bit different from Alan's. (Hope you don't mind, Alan. )

First:
I don't understand the word "must" to show "obligation" in your sentence (as Alan also mentioned), but rather it is used to show that the speaker has already drawn the conclusion that something is true.

Second:
Putting any type of tag question at the end of "You must love her." or at the end of "You must be enjoying it right now." seems like overkill to me. The best reason I can give you for this (my gut feeling) is that by using the word "must", you're indicating that you've already drawn your conclusion and therefore you've already got your answer (yes). Therefore, a tag question is completely unnecessary.

My preferences would be either
You must love her. (no tag question)
You must be enjoying it right now. (no tag question)
--- or ---
You love her, don't you? (with tag question, without "must")
You're enjoying it right now, aren't you. (with tag question, without "must")

I doubt that I (personally) would ever say "You must be enjoying it right now, mustn't you?". I definitely would not say "You must be enjoying it right now, aren't you?" or "You look at her this way. You must love her, don't you?" Not just because it's grammatically incorrect, but also because, as I mentioned, adding a tag question to the "must sentences" also seems completely unnecessary to me.

Just my personal opinion.

Amy

[Alan]

Hi Amy and Tom,

Not really wanting to prolong this more than necessary or to have the last word BUT I think there is a possibility of must .. mustn't even though I accept, as Amy says, it could sound a bit like overkill. Perhaps I can set the scene - someone has made a quite ridiculous suggestion and you refuse to take it seriously and you say: You must be joking or you could say, I believe : You must be joking, mustn't you? and to me that makes the point please tell me that you are joking, please, please.

Alan
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[Pamela]

Well,I absolutely agree with Alan's interpretation.In a sentence"You must be enjoying it right now,mustn't you?" the modal verb "must" doesn't have the meaning of obligation(sure)but "supposition".

[Yankee]

Hi Pamela

My interpretation is nearly identical to Alan's --- just a different way of explaining things and with one "objection". My "objection" was adding the "mustn't you?" tag at all when "must" indicates a presumption of fact or a logical conclusion. I simply attempted to explain the reason why I would generally prefer no tag question whatsoever, particularly for the examples Tom gave.

Hi Alan

OK, I'll admit that there could be a tiny little possibility that I might use "must ..., mustn't" this way on "special" occasions.

Amy

[Pamela]

Hi,Amy!I understand you but the matter is-there is no mistake in using must or mustn't in the second part of the disjunctive questions.Anyway I share some of your points referring to this matter!