If you notice, at no point during Thor: Ragnarok's marketing so far has Hela been described by Marvel or any of the actors as being the 'Asgardian' Goddess of Death, but rather as the Goddess of Death. So maybe it stands to reason that within the MCU, Hela doesn't just govern the dead of the Nine Realms, but rather the entire universe, which of course makes her quite a lot more powerful than 616 Hela.
If we go by this argument, it makes Hela just as powerful (or if not maybe more so) than Odin himself. So just maybe, within the MCU, Odin and Hela are actually opposites of each other, two sides of the same coin. Where Odin is the 'Sky Father' and the King of Asgard which has already been described in the MCU as being the 'protector' of the universe (in the first Thor movie I believe), Hela is the Queen of the Underworld and the ruler of the universe's dead. It would also mean that in the MCU, the realm of Hel is not just the realm of the Asgardian dead, but the realm of all of the dead. We have absolutely no evidence in the MCU to date that the other pantheons that exist in the comics universe (such as Hercules, Zeus and the Greek/Roman pantheon) also exist, so Hela being the Death Goddess of the entire universe doesn't really pose an issue. All this and how Hela eventually came to be imprisoned could be explained pretty easily in a short prologue to Thor: Ragnarok, which is where the Thor series has traditionally introduced the villain and the background to the main conflict in the movie.
So if we go by all that above, it could be argued that Thanos and Hela's first 'meeting' could indeed be very similar to his first encounter with Death in the original comics, which has never actually been fully explained. Thanos, being a nihilist and obsessed with the concept of death (just like his comics counterpart) falls madly in love with Hela, the goddess and ruler of the dead, and is willing do anything to capture her attention and her love and approval in return. Meanwhile, Hela has been causing chaos in the universe because she has been trying to fix the life/death balance which she feels has become off kilter and so begins an epic battle of control between her and Odin who eventually manages to defeat her by trapping her soul within the Soul Stone. Thanos hears of this and enraged wants to release his love from her prison, but knows he has to bide his time because he doesn't have a hope of defeating Odin and the entirety of Asgard without an army behind him.
And so begins Thanos' epic millenia long quest to gain power, build an army, release Hela from her prison (which he helps instigate during the events of Ragnarok because of Odin's sudden absence), gather the Infinity Stones and then prove his love and devotion to Hela by wiping out half the universe and 'correcting' the imbalance that she (and by extension he) feels exists.
Again, the connection and history between Thanos and Hela could easily be explained at some point in Ragnarok, seeing as many people believe that Thanos may have a brief appearance in that movie anyway. Then it's already established and they're good to go when Infinity War rolls around.
t:
That's canon, not something the poster made up. We know Hela has been imprisoned for 'millennia' from the EW article and a direct quote from Cate Blanchett. Loki's crappy governing leads to her 'accidentally' being released. How she became imprisoned in the first place, who did it and why isn't yet known. The part about her soul being trapped in the Soul Stone is the made up bit, pure theory on the writer's part as to how such a powerful goddess could successfully be contained.
