Stinky roommate!

Hey y’all. So my boyfriend is helping a friend out and letting him live with him while he’s going through a divorce. My boyfriend is fairly clean for a guy, and tries to keep his house pretty nice and orderly, but his roommate is from a family that never really bathed often or washed clothes frequently, so he kinda stinks. Like it’s so bad you that we can smell his room through his bedroom door. He’s such a sweet guy, and my boyfriend has no idea how to go about talking about it in a way that isn’t rude or hurts his feeling. I’m not sure what to tell him advice wise, so I figured maybe someone on here could help me think of something. 😅