1 Book Found

Based on your description:

"First book in a trilogy. Author was living in Germany in 2014 when writing this. Main character co-owns an antique shop with someone else. Published between 2014 and 2023. Part of the story is set in the 1910s (historical timeline). Key scene: main character carves their name into a tree trunk to prove they were there. Another key scene: main character's fiancé throws their picture into a fireplace."