On the one hand, I consider hiding money in marriage to be grounds for divorce.
On the other hand, you're lack of knowledge on this issue is clear, and you might be jumping to conclusions prematurely. For one thing, tax-advantaged retirement accounts can only be held individually, not jointly. This doesn't mean he should have hidden it, and it doesn't make it okay for him to have opened one for himself and not for you. Then again, I don't see how it's his responsibility to open an account for you; that's really something you should be doing for yourself, and ideally it wouldn't take your finding out that your husband has a retirement account to get you to realize that.
However, it is just as likely that your husband is equally ignorant, most people unfortunately are. A lot of people, even on the money management board, don't know that a SAHM qualifies for her own IRA even if she doesn't personally earn any income. Employers often automatically sign up employees to participate in their 401(k) plans (with employees having the option to opt-out, which they may or may not even realize in the mound of paperwork they are given), and given the statistics on how this increasing participation (from almost no one to almost everyone), it seems entirely possible that your DH could have a retirement account at work that even he wasn't particularly aware of himself, maybe didn't ever ask for it or want it, and maybe didn't even know he had choices about. Or maybe he's never said or done anything about the retirement account issue because he is lazy. There is simply no savings account easier to participate in than your employer's 401(k); it's easier to check the box than to remember to bring it up over dinner. And it's simply ridiculous to believe this means he plans to leave you; if he has any sense at all, he won't be withdrawing that money until he is in his 60s.
I suggest that you educate yourself on these issues before making any snap judgments. I really like the book, "Smart Couples Finish Rich." It's an easy read and it lays out tons of great information about how to manage your money, set your priorities, save for retirement, and communicate with your spouse about it.