HaBO: Time Traveling Heroine Poses as a Crusade Widow

You did it! We figured this one out! It is a truth universally acknowledged (by me for certain) that the Bitchery pretty much knows everything, and really, it's true. Scroll down to see the solution for this HaBO - and many thanks!

This HaBO request is from Emma S., who is looking for a time travel historical romance. Trigger warning for mentions of animal abuse:

The heroine is a historian from the near future working on a project with a machine that can let people look back into the past on the screen. One night, she doesn’t go to an office party and works instead. But after a lightning strike, the machine actually shows future events. She tells her colleague about that in shock, and said drunk colleague throws her into the machine to transfer her to the past with some expensive fabric and nuts so she will have some wealth then.

A noble finds her when she is transported into the past, and she uses an identity of a crusade widow that she (or her mother) makes up for a historical recreation club meeting(?). The noble believes her and makes her the governess to take care of the castle affairs. Very soon, the noble marries a young bride, and is disappointed because she is plain, overweight, and sheltered.

There is a guest called David/Davis and is a knight sent from the king (the successor to Richard the Lionheart). When a boy servant falls to his death cleaning things under the heroine’s order, he comforts her. As she sees that the bride prays for the boy for a long time that night, she decides that as she has already changed history by causing the boy to die, she may as well help the lady to have a happier marriage

The lady initially doesn’t like her because she mistakes the heroine as a mistress and is relieved when the heroine tells her that she plans to enter a covenant. She helps the lady by asking a local herbwoman to teach her about herbs, so that the lady will do more exercises and grow more confident. The lady also learns archery, and later this skill becomes very useful when there is an attack. The heroine’s plan succeeds and the noble begins to like his wife.

The noble has a very clumsy page. When the heroine knows that the page likes playing music and actually learns from a bard, she gives him chance to practise more, and justifies that by saying the page would cause less problems when playing music

King John visits the castle and when he beats the page (because of his clumsiness) and later the family dog (because it tries to protect the kid), the heroine can’t help but try to save them and ends up making the king angry. The knight saves her by saying that she’s his lover and he’s taming her. Later on, the heroine hears about a conspiracy to kill the king, which she later discovers that the king has already known

The twist: While the heroine falls gradually in love with the knight and struggles about this, she discovers that the knight is actually her colleague. His identity is revealed because he sings a pop song from her time when she tries to ask him for advice what to do with the conspiracy. When her colleague becomes sober the next day, he can’t retrieve the heroine because an earthquake damages the lab and everyone assumes that the heroine has died. He comes clean to the heroine’s mother (former military, I think), and she helps to train him how to fight so that he can take an identity of a knight to find the heroine. He first serves Richard the Lionheart and mentions that the king has made a pass at him. Because nearly two decades passes for him before their last meeting, the heroine doesn’t recognize him. And as the colleague has never paid attention to the heroine before that, he can’t recognize her either and actually struggles with falling in love with her, who he thinks is from the past. They make up and later return to the future after telling the noble that they are on a trip or something like that.

The heroine learns that the noble and his wife live a long life and have a lot of kids, and their descendants raise very good dogs and horses. Because the lady tells her that her grandmother is actually Richard’s mistress before, the heroine wonders whether Richard has ever known and muses that the descendants are possibly of royal blood.

This is a stunning amount of detail for a HaBO, so surely someone knows this book!