(this is kind of long)
I've been a tither for over 20 years now. My personal experience has been that times when I didn't tithe--somehow or ever, I wound up coming out of pocket with more expenses than what I normally had--for instance, I would have to get a new lock for my apartment because it broke right at the time when I decided not tithe.
Coincidence or not, these things happen.
I have also learned that when I tithe, I am blessed with more material things when I'm not looking for it. Two weeks ago for example, I had tithed off my paycheck as usual, my laptop broke. I said to myself "Lord, where am I going to get the money to either repair or get a new one [since my laptop was 5 years old anyway]?
I kid you not, at work, an employee left the company and as we were returning the employee's laptop to our computer department, I inquired if I could purchase one from the company [when I was told that the older laptops are given to scavengers for free who sometimes take the parts/or melt the older models down]---the technician looked at me and said "here you go--keep it---we give these away all the time and company is fine with it because we have a policy on how old the equipment is supposed to be for us to continue to use it." What an incredible blessing!
I personally don't call it a coincidence I call it a blessing and an answer to a prayer.--Is it because of tithing?--I don't know, I just know this wasn't the first time it happened to me. I receive things just in the knick of time.
Please understand, I don't tithe because I want God to give me things. I tithe because it is biblical and I love the Lord and want to assist in the ministry and uplifting of His Kingdom. The things he blesses me with are just fringe benefits. If He never blessed me at all with things that I personally think are soooo important I would be okay with it because he blesses me in ways that it takes me a minute realize he continually takes care of me. If I didn't get the new laptop, still have my health, if I didn't have my health, I still have loved ones, if I didn't have loved ones, I'm still alive, if I'm not alive, I'm resting in safe in His arms.
Regarding the husband who won't tithe---I suppose it is a 'whosoever will, let him' tithe. One thing about God is He lets us make up our own minds about everything. It's the husband's right to that choice and Jesus teaches us not judge because of it. If you take your hands off it, God's will is going to be done regardless.