No, it isn't. You have no verb in the main clause "How long". You can fix this by putting one there: "How long has it been since you got married?" "How long have you been married?" is probably the simplest way of asking.
Does this sentence "How long have you been married"? has different meaning than the first one? Does it also convey the meaning that one is asking -for how long the marriage was going on?
Can these kind of other sentences are made in the same way. Like-
How long has it been since you finished your graduation?Can be written as "how long have you been finished with your education?
How long have you been awarded.
I am quite confused if you will explain a bit it will be helpful.
Thanks
How long has it been since you graduated or since your graduation?
How long has it been since you finished your education?
How long has it been since you received your award?