I believe the reason is because, my husband spent a lot of time with my girl when she was a baby. He would hold her to sleep, help me bathe the girl, etc. And later on, when I was pregnant with my son and often tired, he would take the girl out with him to the park, supermarket etc so that I could get some rest. So he has a close bond with the girl.
When my boy was born, again, the same thing happen. He would often take the girl out so that I would have some relief to spend time trying to breastfeed the boy without interruptions because I had a lot of difficulties breastfeeding. He would still help me bathe the boy etc but his time had to be divided because he had to help me look after the girl.
As a result, my boy is not that close to him. They didn't get a chance to bond. I always try to find things for them to do together but it did not work. The boy always preferred me.
However, recently, I noticed that they have started to bond more. This is because my husband would spend every evening coaching the boy in his Maths. Oh, he is a fierce teacher and he would often scold the boy, sometimes till he cries but funnily, my boy now no longer rejects him and would look for him more and more now.
I believe that bonding is a process of doing things together. It need not only be fun activities. It should be daily activities. Bathing, feeding, talking, teaching. I believe that these daily simple activities are very important for parent and child bonding and if left to a domestic helper than you would have lost the most precious moments of bonding with your kids.
My husband had less opportunity to bond with his son the way he bonded with his daughter when she was a baby but I am happy that they are catching up now. Its not too late that they are catching up now when he is 5 years old. :) My husband shares a very special bond with my girl and soon, I hope he will have his own special bond with his son too. I am very glad to see this happening now. Before this, I was a bit worried.
Speaking of bonding, I feel that my husband and I share another bond now compared to those days when we were just a couple. This bond is the bond that comes from our mutual love for our children. :)