Midlife crisis, another woman, problems at work, addiction, loss of income, a medical problem, physical & or mental illness disease, he may just want out. There's only 1 way to know for sure and that's from his mouth, you may have to set up a meeting with a marriage or relationship expert. If this is very new it might just be a phase or something he's going through
This can be a sign that the husband is stressed and is going through a rough patch in his life. It can be also be a sign that he is getting a lot of pressure at home and he would do anything to avoid being home. It is wise for the couple to visit a counselor who will help them solve the problem they are facing.
Don't take this the wrong way, but I think you need to leave him to whatever he Is doing. Many women are to interested in their lovers life. Not to get into your life but if he still gives you good attention and he shows that he still loves you don't worry about it.