Should I (27M) recommend to my friend (26M) whether he should meet up with his ex-girlfriend now that he is in a new relationship?

Get ready, because this is going to require some explanation. Also, I’m using a throwaway account since people are aware of my main one. Early last year, my friend (27M) started seeing a girl (26M) who is a bit older than him (unsure of her exact age). They really hit it off and made a cute couple. Unfortunately, they didn’t have much time together because she was already set to move abroad for work shortly after they met. My friend was reluctant to pursue a long-distance relationship, fearing he wouldn’t be able to handle it. She agreed that it was likely for the best, given that her return didn’t seem imminent at that time. After she moved, she quickly revealed that she didn’t actually want to end things. My friend thought it over seriously but ultimately chose to stick with his decision. They remained in touch throughout the summer, texting and video calling frequently. He often shared updates about her with me. She visited for a few days in the autumn, where they talked things through and "officially broke up." Even after that, they continued to communicate. Although he was the one who ended things, I can tell he has struggled to let her go. He frequently expresses a desire for her to remain in his life, though he claims to want her as just a close friend. Personally, I believe he may not be fully honest with either me or himself. About a month ago, he began dating another girl he had been in contact with for a while. He seems to like her, but everything is still new. Recently, he learned that his ex-girlfriend will be moving back to our country later this year, just two hours away. Next week, his ex is visiting town, and he plans to meet up with her several times. As far as I know, she won’t be staying with him and is mainly coming to see other friends. I know her trip was planned before he started seeing his new girlfriend, as he mentioned it before the holidays. He’s excited to see her again, but I can’t help but think that the new girl wouldn’t be thrilled to learn he’s spending time with his ex, given their history. I’m unsure how much he’s disclosed to the new girlfriend, if anything at all, and I suspect he hasn’t shared the full story. Now, I’m torn. As a good friend, I feel I should advise him to avoid meeting his ex out of respect for his current relationship, especially if he wants that to progress further. However, I also want him to pursue whatever makes him happiest. His excitement about seeing his ex suggests to me that he might still have feelings for her and isn’t fully acknowledging that, especially now that she’s moving closer. Perhaps he needs this meeting to clarify his feelings. So, kind strangers, what should I do? Should I discourage him from seeing his ex for the sake of his current girlfriend, should I support him in reconnecting with her, or should I just let things unfold as they will? TL;DR: My friend and his ex broke up because she moved away. He recently started dating someone else, but I suspect he still has feelings for his ex. She’s visiting soon and moving back closer. Should I advise him against meeting her for the sake of his new relationship, or encourage him to figure out his feelings for her?