Hard to say what's going on, we may need a little more info. First, are you circumcised? I'm guessing not, since you mention the foreskin. It sounds like something you're doing during intercourse is irritating it. Perhaps the sex is rather vigorous, and if there's not enough lubrication, that could cause this type of irritation & redness. Maybe you & your partner could try using one of the lubes that are readily available & see if that helps