我建议覆盖两个geom_link_edges --第一个是节点之间的完整链接，第二个是末端有箭头的部分链接。我可以用你的例子来实现这一点，如下所示：

library(ggraph)
library(ggplot2)

# make edges
edges = data.frame(from = c("A", "B", "C"),
                   to = c("C","A", "B"),
                   relative_position = c(.6,.1, .4))

# create graph
graph <- as_tbl_graph(edges)

# plot using ggraph
ggraph(graph) + 
  geom_edge_link() +
  #this the partial link with the arrow - calculate new end coordinates
  geom_edge_link(aes(xend=((xend-x)*relative_position)+x,
                     yend=((yend-y)*relative_position)+y)
                  arrow = arrow()) + 
  geom_node_label(aes(label = name))