Originally Posted by catfeeder
The only platform for that is honesty. So be honest with yourself, first. Decide whether this man's attachment to this child is acceptable to you. If so, then remove any barriers to him seeing the child--and then he won't feel a need to lie to you about it.
This.

My gut on the situation (just responding to your gut) is that he has no romantic feelings toward the ex but remains attached to the child and wants to be a part of the child's life. And all that is okay, even beautiful, something to be celebrated, not concealed. But he feels "bad" about it all because it's "complicated"—and perhaps because he believes, in his gut, that you can't genuinely handle this truth of his.

And so he edits out that truth with a lie—not a lie to hide nefarious behavior, but one to protect you from the parts of him he worries are too much for you (and maybe any woman) and your connection (and maybe romantic connection in general). Everyone we meet and connect with comes with some sh*t; those worries are part of his.

These sorts of lies, in my opinion, can be the most destructive. Because what they do is act as an impediment to a deep, honest, authentic connection. If he is downplaying something important in his life, he is, in essence, downplaying himself, showing you only shades rather than the full picture. On the flip side, while you may be frustrated on the surface that he is spending time with an ex and her child, the deeper frustration comes from feeling closed off from his full, authentic self—and it's in that frustration that the mind jumps to some looney thoughts of spying.

Not to set a trap so much as to just be closer.

But no. Traps are traps, no matter the intention. Spying and deception have never, in the annals of human history, brought two people closer. It's acting from a place of insecurity, paranoia, and control, and as such will only make things more paranoid and insecure. It's like trying to fix a crack in a foundation by blasting it with a hammer instead of carefully treating it with putty.

What he likely needs—and the tricky part here is that he may not even know this—is not just someone who will put up with this part of his life but who will value it, and what you need is to ask yourself if that can really be you. There is no wrong answer, only the honest answer.