Alzheimer's.

The caregivers on this site vary greatly in age, economic situation, the kind of disabilities they deal with, the relationship with the care receiver, and other details, but the one thing the vast majority of us have in common is finding caregiving "so much harder than I thought it would be." There is just no way to anticipate this until you do it. I suspect that it is harder for you than your wife understands it to be. It is just too hard to grasp until you have done it for many days.

By the time your wife comes home at night you are both so tired from very long days I doubt that you have a lot of high-quality communication time. Sigh.

Does MIL require constant supervision? If she can be left alone for a while you will have more options, but assuming she can't be alone, one of the really great options is the one vegas lady already mentioned -- adult day care (usually called adult day health programs). This has to be set up on a schedule (rather than drop in) but the days and hours can be very flexible. My husband went 9 to 3, 3 days a week. Some people there went every day, 7:30 to 5, while their caregiver worked. Others went just once a week. A simple breakfast and a hot noon meal were available. They also had services such as helping with a shower and trimming toenails. If MIL is on (or is eligible for) Medicaid, in many states the day care service is paid for through the waiver program.

OR ... find a volunteer program or hire a companion (with MIL's funds) to come in for a few hours each day. Go meet your wife for lunch. Golf. Join a daytime bowling league. Do something that gets you out and talking to other people.

Get on AgingCare daily. Answer other people's posts. Post your own concerns. This is a meaningful kind of "talking to adults" every day.

I used to get up "lunch meetings" with a friend in another state. We blocked our calendars, ate our lunch, and talked on the phone. Sometimes I had to go and do something for my husband, but usually we had the scheduled time to ourselves. Do you have friends who are available for a phone date during the day?

Join a caregivers' support group. If possible, find one that meets during the day and arrange for care for MIL. If necessary, though, do it in the evening when Wife can be with her mother. I hate to reduce the limited time you two have together, but a support group is worth it.

This is hard. You are isolated, making it harder. Your wife may appreciate what you are doing to the nth degree (let's hope so) but even she may not truly understand what you are going through.

It may be work to arrange it, but get some time off from the caregiving, and break out of the isolation. You are worth it!

Look into adult day care for the MIL, or some type of in home caregiver to give you respite. A caregiver can come in and set you free for a few hours to get out and play golf or swim or work on your hobbies. Ask her doctor, or yours, about resources in your area. You didn't say what specific problems were harder than you thought....eating, bathing, other ADLs (activities of daily living) or confusion, combative behavior, etc. More details on specific issues will generate more ideas for you. Does MIL really need nursing home care?