During the conversation, my papa (a male supporter) told me, “We only see the good in each other.”

You’ve never posted a question here before, have you? ① He was implying that he hasn’t shown you his bad side yet—basically hinting that he might let his guard down and reveal it eventually—and confessing it gives him a sort of get-out-of-jail-free card. Another possibility is ②: “If I’m like that, then you haven’t shown your true self either, have you? You’re just pretending to be a good girl, right?” It’s a bit of a sarcastic jab. I think the reason he makes comments like that is rooted in self-loathing—because he knows he’s like that himself. Long story short, he’s a somewhat cynical and difficult man. If you want to keep the relationship going, the best response might be: “I understand. Thank you for always showing me only your good side. I appreciate it.” But if it rubbed you the wrong way, you’re probably better off ending things sooner rather than later. In the long run, your personality differences will build up stress and eventually lead to arguments.

I think they’re simply confirming that, since you’re not seriously dating as boyfriend and girlfriend, your relationship is only a superficial one mediated by money. Still, it’s not something a papa (a male supporter) really needs to say out loud. Personally, I feel that even if he thinks it, he’d be better off keeping it to himself...

I think it means exactly what it says. If you’re not planning to get married, there’s no need to go out of your way to show each other your bad sides.