The reason why he didn't want children is probably because of the curse in their bloodline where the mother dies when they give birth. And reason why he did what he did when he found out she was pregnant was because she didn't want her to die. It's in chapter 127. Spoiler: This part All he peeked at was the fragmented past, but Lennox understood the situation as if he had seen it in person. If Juliet knew, she would either insist on giving birth to a child with the risk of losing her life, or she would abandon him and run away. And his choice was obvious. Even if he is in the same situation over and over again, he will not be able to hold Juliet greedily and let her go. Lastly, about his feelings. Based on my understanding while translating, he has long realized it but he just hasn't admitted it yet. Hope this helps.
The more we learn about spirits the more I wonder why juliette's seems so tame compared to the others...