Many people come to the U.S. as tourists to marry. The potentially complicating factor in your case is that you intend to marry a U.S. Citizen, and that could raise suspicion that you don't intend to return home at the end of your authorized stay. However, you don't need to volunteer that you intend to marry and it is unlikely that the immigration officer is going to ask.

Incidentally, if you intend to eventually move to the U.S., a fiancé visa is normally faster to obtain than a visa for a spouse, but is also more expensive.