I went to Korea to study in March this year, but I can't bear to part with my boyfriend. If I want to maintain this relationship, I may have to stay in Korea for 7.8 years.

If you have a good relationship with him, or if you really care about this relationship, you can invite him to go to Korea with you, or not to study abroad (but it is best not to). You can also do something that he will never forget, leave a deep impression on him and make him think that you are the best choice, but 7 8 years is too long to maintain a relationship.