Marc Thompson said the "hardest thing is not knowing" where his twin brother Ben is.
The 34-year-old from Haverfordwest has been missing since Saturday, after he watched Wales' Six Nations game at the Millennium Stadium.
He told our Correspondent Carole Green that this would be "very out of character" for him not to contact his family.
More top news
Regional results for the Assembly elections have been announced this morning.
The morning sunshine will soon get to work, with rising temperatures and sunny spells for all!
Results for constituencies across Wales are being announced. Find out the details for your area.