to begin with, i want to tell you that even if that person is not yours, it does not take away anything from the love you hold for them or diminish its worth. Neither does it invalidate how you feel nor does it mean you aren't allowed to grieve their absence. Now, from what you've said this person is leaving in the next few months right ? so before they do, you still have time that you can spend with them even if it is once a week. I know, I know it is way easier for me to say than do it in reality but what if you tried to make the most out of the time you do have together? The present is heftier than the future we do not know of so stretch today a little longer. You told me that you care about this person ; a dear friend wrote a while ago that the best way to love someone is to let them know. If it is possible for you to make your feelings known, give it a go. Or at least that they are important to you and you care about them. Distance plays a big , big role but i believe the love we share with another person, even if they are oceans away, finds ways to overcome that stretch of distance between. You do not need to punish yourself for feeling a certain way, cherish today as much as you can and make the most out of it. Of course, i do not know the entirety of your relationship with this person or how the situation stands but if you can let them know, then do so. You still have months , and many more words you can tell them and within this time, you can also find ways together as to how to stay in touch. I hope your heart feels lighter soon. Grief is often a part of loving someone but grief is not all that there is to it. Sending u hugs 🙁