Is it appropriate to comment on another with a "😍" on another girl's picture?

So I have a partner - we are not in a committed relationship but there are still no other people involved. We've been through a lot together, I moved countries and he still visited me. Always made time for me and the likes. Along the lines, we both started liking each other. But we can't be together because of certain circumstances (our age difference is a bit too much). But we still value each other and care deeply. He's mature, communicates well and understands me. Yesterday he devoted his entire day to me, asked me to be his valentine and wrote me a 7 page handwritten letter. To keep this short, he commented on some girl's picture with a "šŸ˜" , I'm not jealous. I can't tell if I'm feeling insecure but I do know that I feel like he didn't think of how I would feel when I would see it. We have a 2 weeks vacation upcoming in a week and a half. How do I communicate about this or do I just leave it and bring it up on the vacation?
Is it appropriate to comment on another with a "😍" on another girl's picture?
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