Help with writing translation

Hello,

I was wondering if someone here could help me with a small item. I am dating a girl who is Okinawan, and plan to propose to her in Okinawa. Her mother and grandmother are native Okinawans, and I am currently working with a Japanese company to create a custom bamboo engagement ring box. I intend to engrave 4 words that encompass our relationship on the box, but written in Japanese.

Would anyone on this page be able to assist me with transcribing the words in Japanese?