Despite the few interactions between Splendid and The Mole, it is shown that they are not fond of each other at all, likely due to Splendid's impatience and The Mole's blindness clashing whenever they interact, generating a conflict. It could be argued that their conflict is one-sided, as The Mole shows less signs of disliking Splendid than vice-versa.
Splendid is shown to harbor great contempt towards The Mole. Though it isn't certain when or why this started, it is first shown Gems the Breaks as The Mole becomes his first intentional kill and only intentional kill that was out of personal anger and not to defeat a criminal. In See What Develops Splendid gets very annoyed at being paired with The Mole and when he got a picture of him changing out of his reporter personnel, Splendid goes to very great lengths to try to stop and possibly even kill him. He also doesn't show much concern for him in group scenes compared to other characters.
The Mole's Side
It is hard to tell what exactly The Mole thinks of Splendid. On one hand, in Gems the Breaks, The Mole becomes annoyed at Splendid's laser beam slowing down traffic and honks at it (though it is unknown how he knew it was there in the first place). On the other hand, in See What Develops, he has no problem with working alongside Splendid, suggesting that the conflict is mostly one sided.