Goose is a very loyal bird. After the goose died, its partner could never find a mate. Moreover, the lonely goose who lost her partner has a very low position in the flock, so she stands guard, forages and works hard.
This poem describes the lonely goose's hard environment and the pain of losing its partner. It is better to never fly alone than to know that you will leave on the journey, leaving me alone and sad to recall the pain of losing you. Why not form a partner with you in the first place and leave me alone? The poet's touching the scene can also be extended to the portrayal of where you will go between lovers.