Competition for affection

Now that Eli is smiling, I realize that the challenge of two kids is not just a competition for attention but now affection. When Eli first smiled at me when I was jumping him up and down, I was happy that he was smiling and also a little sad that maybe half of my smiles originally slated for Tobey when he was an only child, now go to Eli. Of course ideally I double my amount of smiles so there's enough for everyone to go around but as I see my energy and patience level sometimes limited, I am sad to admit that now my affections might be split, not doubled, between the two. There are times that I feel bad for playing and smiling and cooing with Eli in Tobey's presecne. Weird that I don't feel the same when the reverse happens since I assume that Eli doesn't really know what's going on anyway. I wonder if any of this is related to Tobey's recent whininess, if he notices that I struggle with sharing the smiles.