When trying to figure out whether marriage -- and your investments -- would make your husband-to-be ineligible for VA medical benefits, he has to learn whether his eligibility for those benefits is based in part on his income and asset level. That's because some veterans are eligible for medical care based on the specific nature of their military service, regardless of income and assets, while others are eligible for medical benefits only if they have low income and few assets. If he's eligible for VA medical benefits regardless of his income assets, then marriage wouldn't affect his eligibility. He can get this information by checking with one of the V.A.'s Vet Centers in your state or by contacting the V.A.'s Veterans Benefits Administration office nearest you. He can also call the VA's toll-free telephone help line, at 800-827-1000.
If it turns out that your husband-to-be's VA medical benefits are dependent on him having low income and few assets, you might consider having a lawyer -- it should be one who specializes in what's called "family law" -- prepare a prenuptual agreement for you, which would keep your investments and all income from them as your separate property after your marriage. This is a legal document that would mean that your husband-to-be would have no access to your investments or income from them, so that legally that money would not be counted as "his" by the VA. You need to let the lawyer know why you want such a document, and as part of preparing it, the lawyer should check with the VA to make sure that the terms of the agreement satisfy VA rules regarding your husband-to-be's status.