My bf does this on a regular basis and he hasn’t had any problems.

Actually, yes – your veins can get scarred. I give a single-arm triple platelet donation every two weeks. Over time, my right arm vein has become scarred. The Red Cross phlebotomists are very good, though, since they know me (and my vein) and are very careful to not stick me te same place twice in a row. Not a big deal though, especially since platelets are so valuable to cancer patients.