Caspar and Finland, together with Lauriel, decided to stay longer at Targu Mures because they wanted to enjoy more time with their grandchildren. The two men spent a lot of time exploring together accompanied by Altair and Vega, while Finland helped Aleksis with Ireland and Scotland.
Finland was very fond of her youngest grandsons because, for the first time, she felt like she finally had family members who looked like her. Caspar and all her children have mostly European appearances, while Finland was the only one with half Asian and half European look.
That was also one of the reasons why Finland really liked L. The girl was half Japanese from her mother's side, and she looked like Finland. Unfortunately, the love story between London and L did not go smoothly so Finland could not expect to have L as her a daughter-in-law.
All I can say, London and L will have their happy ending, but it will take time :).