I'm a little concerned about how he hasn't kissed her because you told him not to... Chances are that's going to happen... and then he's going to feel like he lied... and will continue to NEED to lie... one leading to another.
Also, you make think it's a just a freindship... but for him and her it's more than that... They aren't looking to get married... but there generally is some sort of exclusiveness to their friendship...
Mostly, it's important to keep the communications open. They are both hitting puberty... hormones can rage... and without solid information stupid choices are easily made.You can't really tell them which choices to make... you have to educate them as to why your desired choice is the best one...
Also, I have to say to moms of girls... my mother always had a VERY open forum for communications... We were allowed to have boyfriends whenever they emerged... we were "coached" on the lines that boys offer... and were taught all about self respect.
I met and started dating my husband at age 15... we didn't get married until we were 25... I made him wait for sex for a REALLY LONG TIME... a few things: his mother always treated me like I was no one important that our relationship wasn't important... really nothing more than a friendship. Her treating me like I was very insignifcant has continued... she still looks at us like we're 15. Her choice to treat us like stupid little children has kept her from ever really seeing us as adults.it's a really WEIRD situation....
Also... EVERY GIRL I KNOW that was made to wait until she was the magic age of 15 or 16 to date... who also had few conversations about anything important with her parents... had SEX while in highschool (way before they were allowed to date)... were the only girls who I know had abortions... and had multiple partners before high school graduation. These kids were only given rules... and no guidelines or open conversations... they hid their desires, concerns, etc... They got into way more trouble than any of the kids I observed who were allowed to explore relationships with some guideance...
Good Luck!