I would compare when we two parted with the winter swans because they are both to do with a relationship and have rain involved In it that is why I think these two poems are comparable

To key points of the poems is

Relationship because they both are about a relationship that might be falling apart

Negative tone because in when we r two parted has a negative tone to it

A very gloomy scene in both because they are both raining and have a very depressing feeling to it

and both of them have a something to do with both of the characters and about their story