Q. One that is getting married on Lag Baomer late afternoon, does one have to fast the traditional fast of chasan kallah if one finds it difficult?
A. Mishna Berura (573: 7) quotes different opinions if one should fast in a day when when no tachanun is recited. Mateh Efraim (625: 2), Daas Torah (573) and others are lenient when in need.
Horav Shlomo Miller's Shlit'a opinion is that if possible they should fast half a day, and after they daven mincha, they may break their fast.
Rabbi A. Bartfeld as revised by Horav Shlomo Miller Shlit'a