Hello and welcome to HCM
It seems that your boyfriend is suffering from Fistula in ano. The choice of treatment in this case is surgery by excising the track of the fistula and regular aseptic dressing. Recently Laser surgery
are also available but I don't know the results because reoccurrance of fistula is very common.
The other alternative procedure is Ksarsutra therapy in Ayurveda.
So consult your doctor and get the treatment which suites you the best. Till than do the regular dressing and take a course of antibiotic if pus is coming out.