so after she did in the explosion.. she was reborn as a living thing and was raised for 20 years... so that's why it's a time skip.... well it's not that bad... atleast they could have made many scenes after they meet again after 20 years.... they couldve atleast show the scenes of every character...
This ending shows that love can wait for many years and even a lifetime... and Suguru waited her for 20 years that's a sentimental memory ok