My boyfriend has had weak erections lately how do i talk with him without hurting his feelings?

Very common: Make him aware of what you have noticed without being critical or angry, and let him know how common it is. I had a similar problem with my ex-girlfriend, but she would start slamming doors and vandalizing cars in the parking lot to show her frustration. Don't do this. It makes a bad situation worse. There is a laundry list of potential causes, such as stress, medications, alcohol, and nicotine.