If someone broke into my house with intent to cause damage or harm, I would protect my daughter as much as I would everything else I own. What's mine is mine and I'm very territorial.
I have seen envy in people who are bitter, who cannot see positive things in life or themselves. They can't love, and they take for granted they are not loved even though they want to. They could possibly love if they had a totally different take on life. Often they see their loneliness and lack of love as their only issue even if it is not true.
The rest who cannot specifically feel love, they don't know what they are missing. It seems more like they look down on love or wonder what the heck it is for. I think I love my kitties and the doggiedog, but I can't see how it is possible or even wanted to feel that about a human. There is something ridiculous in that notion.
I care quite a bit despite not feeling love. I have grown accustomed to some people to the point it would be very painful if they disappeared. But that takes many years and a big part is habit and knowing who they are. I also feel responsibility for others. I think that sets me apart from people who are much more cut off from others.