Should I let him go, or give him one more try :'(?

I met this guy on a dating app and we've dated twice. After that, I left his country. It became some long distance thing, and we both deleted our dating apps, but not a relationship. Last week, he decided to go back on the dating app.

Tbh, I'm not happy about it, and tried to communicate with him. All the time, when I brought it up, he felt I was trying to argue with him, while I was trying to make things clear.

I wanted him to choose between me and the dating app, and obviously he chose the later, but is not willing to let me go. I asked him about his intention on the dating app, he said "No intention. My intention is to go on date 3 with you."

And when I told him I feel it doesn't make sense that after we've been talking to each other for 6 months & 2 dates, he still wants to go back to the dating app. He said 'Doesn't make sense? Not like I went on dates or anything."

I told him if he's gonna date others, I'll leave immediately. I just don't feel comfortable when he told me "I miss you.", "I like you" etc. while talking to other girls and maybe thinking about dating others.

It takes longer time for him to reply to my messages these days. Maybe he's getting bored because the honeymoon phase is over. Now I'm about to go back in a month, but I feel I need to make it clear if he's keeping me as his backup plan, then we shouldn't continue this...

If you were me, would you decide after meeting up in real life again? Or you'll directly move on?

And if you wanna set boundaries, what will you say? I feel telling him "If you're only keeping me as your backup plan, then we shouldn't continue this" sounds pretty rude.

Thank you

Updates
4 mo
He went back to the dating app in the beginning because he thought I deleted/blocked him on social media, so he got mad and went back for "distraction". But then he has been back for almost 1 week, and I feel "distraction" is just an excuse.
Should I let him go, or give him one more try :'(?
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