Can my future husband claim part of this condo in a divorce?

He can make a claim for the enhancement in value of the condo, yes.

Generally, even though the condo was your separate property prior to marriage, if you make mortgage payments with income you earn during the marriage, like from employment, that income is marital and the condo, though still an essentially non-marital asset, will acquire a marital component, the value of which will be determined at the time of divorce in accordance with a case call Kaa. There are things you can do before getting marriage to try and protect your pre-marital assets, such as entering into a prenuptial agreement. Consult with an attorney to discuss the specifics of your situation and your options.

The answer to your question is yes. Payments made on the mortgage after marriage are a marital investment. So, the interest that the spouse accumulates is one half of the mortgage reduction after the marriage.