My boyfriend has IBS and he's not able to clear his bowel properly so please tell what should he eat inbreakfast, lunch, dinner and what he should avoid?

Controversial. Unfortunately, the evidence on what works in a diet for ibs is not strong. The traditional recommendation is high fiber. However, some people have more gas than any other symptom, and thus avoiding gas-producing foods may help. Some people may also be sensitive to gluten or other allergens. The best advice is to see his provider and a nutritionist.
IBS. Ibs causes constipation and sometimes diarrhea. As a general rule, i think he should take fibers daily, and see a doctor if he needs medication.
He knows. Each ibs patient gains a pretty good handle what is bad for them.Many new rx's have come on the market and a visit to a G.I. Dr. Should be considered.