My understanding from friends who went through this process along with a lawyer I spoke to awhile ago said that him traveling to the US is "risky" and a "grey area" b/c there is a concern from the government/border agents that he will come in and get married and change his status while here. They all advised for us to travel together outside of the US, but this is highly inconvenient to me b/c I am a full time single parent. That is why I wondered if we were all ready married, then his entrance into the US for visitation could be less "risky" and easier.