My husband is really starting to scare me?

He's NEVER acted like this before and it's really creeping me out. He is ALWAYS staring at me, CONSTANTLY. I get kinda nervous and give him little smiles but he just keeps staring. He acts pretty normal other than that. Other times, when he thinks I'm sleeping, he caresses my body. I wake up and ask if he's feeling... You know... ANd if he wants to... You know. He always just says "no" and pretends to go to sleep, and then starts touching me again when he thinks I'm asleep. Also, he is yelling and cursing at our children a lot for minor and stupid reasons, like when they laugh too loud or set the table wrong. I'm really worried. Is there ANY explanation for his behavior! I'm just hoping it's something most men go through, or some sort. Of midlife crisis.