i do love and respect the idea of the world at large being stunned at finding out how long ilya and shane have been together, but i truly think that under NO circumstances would shane ever choose to offer ANY personal details about himself or their relationship willingly.
which combined with ilya loving just making things up and saying them (as seen in the "yes, the rumors are true-" scene) offers the very funny idea that ilya actively tries to offer as much privacy as possible by just throwing out stories about them at random so there IS no central story for people to hound shane about.
assorted backstories a la "ilya just started talking and found out with everyone else where he was going with this":
they got snowed in at all stars one year (b-but wasn't that year in florida?) and decided there was nothing better to do
it started as a bit and neither is willing to give up first
they paired off to combine forces like nato
they paired off to limit how many kids they could have in the future to make sure hockey stayed fair
ilya lost a bet six years ago
shane lost a bet three years ago
ilya got tired of remembering phone numbers for his hookups and shane's is easy
ilya got tired of having to look things up in english and french when talking to other people and decide to marry someone who speaks two languages to save time
shane is gifted enough (wink wink wink) that other people are cowards and only ilya was brave enough to rise to the challenge (this one gets him in trouble on the phone later but it also gets him laid that night at home and also confuses the online speculation about who tops and bottoms, so net positive tbh)
yuna hollander is the best manager in the business and a political marriage was the best way to secure her services longterm
with the end result that all shane has to do is shrug and "my husband has already told our story a thousand times by this point. no point in repeating it and boring people." in interviews to get out of people trying to dig into things he doesn't want to tell them.