Possible ED situation

I think my boyfriend may be experiencing some kind of erectile disfunction and I’m not sure how to broach the subject with him. We’ve been seeing each other for a month or so now and we’ve been intimate twice. The first time he blamed it on having too much alcohol because we were at a party earlier in the evening. The second time he had a little trouble getting and staying hard. I don’t know how to talk to him about it without saying the wrong thing. Any advice would be greatly appreciated