Why is my father this way? Why cant he show any simple love or initiate even a convo these days?

He is a single father. He has fathered 2 children for like 11 yrs of his live singly. He can be too militant sometimes. Before it wasn't so much like that until the last past 5 yrs. My sis hasn't been the greatest daughter for the last 4 yrs. I have been pretty good on the other hand. That proly hasn't anything to do with this the question I'm going to ask. I've always looked up to my pops. Always go give him hugs. My sis never did. I would literaly knock on my pops door just for a hug before I went to bed. When I was lil all the way up to now even just never knock anymore. Its just hugs here or there, if I hadn't seen him in a while. He always has his stupid door locked with him in it. Has for 11-12 years. Don't get me wrong he comes out and watches movies and stuff or we go out and run or whatever. But not as much anymore. But lately last past 2 yrs and 6 mo he has had GF and all and a new place. He works almost all the time and only the weekend to recooperate & all. In which he stays home on Saturday till night. I'm in my room with the door locked and he's in his room with his door locked. I have a lock on my door cuz my sisters a theif. He has one on because of the same thing, O other things which I'm not certain of. My problem is. Me and him are home...my sis has boy F. So she's at his place. Right now its me & pops home & our doors are locked. I hate this! Its so weird like. He doesn't even hug us, or complimet us, or show love 2 us. My sis has dated wrong men because of it so she says. I haven't. I handle things dift. I member we were in church & the pastor was telling everyone to show 2 eachother & put your hand on next 1 2 u's lap. He hessitate doing a # and it just seem so unnatural. Why is he this way? He said his mom never showed love, but why wudnt he say I'm not gonna be that kind of parent, like he said so many other things regarding dift issues w/ his mom & pops really. Who wasn't in his life? He's been a great father. Just this is just weird 2 me.