It is better to let nature take its course, accept the present results, learn to be content, and be satisfied with the problems and feelings that will be faced in the future than to be miserable after losing your lover and never get out of this dark day. I can see that your girlfriend is very open-minded about feelings and thinks that she will accept any situation in the future. Although she is a little sad, it is also a sign of growth.
"Happy-go-lucky" is an idiom in China, pronounced as suí y and rā n. It means being able to adapt to the environment and be satisfied under any circumstances. There is also a feeling of being stuck in a rut and afraid to change.