I think that a parent talking to their kids about sex, hormones, their bodies, abstinence, respect for themselves and their girlfriend, love, responsibility, why God believed that it should be done in the sanctity of marriage and their soon to be best friend rosie palmer should all be taught. Many kids are confused by their hormones, the "everybody is doing it" argument, what they think love is, etc. That is where parents need to step in and help them. When I was 15 (20 years ago) I was not dating, I was only at chaperoned parties (yes, phone calls were made) and the homes I was having sleepovers at would never allow boys there, etc, the parents were like mine. Parents should not turn a blind eye. This boy's mom needs to ask him why he thinks he needs to or is ready to have sex and how his girlfriend is feeling about it, just for starters.
I should do more thinking about this myself (my boys are 14 and 17): I can see how a parent hesitates. But a boy asking for a condom has definitely issued a challenge: he may be testing to see where the limits are.
I would definitely do two things: (1)talk to the boy about what God expects him to do: to abstain from sexual intercourse until marriage. Acknowledge the profound strength of temptation, but make the law of God plain. (2)get on the phone to the girl's parents and discuss what should be done to help the young people maintain upright behavior.