My best friend made hier bf cum in his underwear

So my best friend is 20 years old and has never done anything more than kissing. Shes always been worried about but i keep telling her itll come when itll come and she should be selfconcious about it. So when i saw that her and an another friend of both of us seemed to be into eachother, i kinda puch them into the others arms and now theyre dating. Im really happy for them obviously.

Keep in mind though, he is younger (18 years old) but he still have more experience than her, since shes a virgin.

This morning, she announced that she "made a boy cum for the first time" and she was glad of it, so was i. The first thing i thought was that she jerked him off you know. But soon, she clarified she had not used her hands (so with friction and too much excitement). My first response was something like "dont tell me he cumed in his pants?" But i meant it more like a joke cause to me its kind of a funny situation. He did cum on himself and his clothes you know. This has never happened to me and i always saw this as something that happens to younger and inexperienced people, which they are and thats totally fine. But she got really offended by my reaction and said she felt dumb because of me which was not at all what i wanted. I went on to clarify that the important thing was that her and her new bf were happy about it, and that i was happy for them.

I feel bad because she seemed hurt by my reaction. I dont really know how to explain to her that i hadnt thought she would have seen something like this as an important step in her sexuality, cause i would personnaly maybe have been embarrassed if my bf came in his underwear. Im guessing easily that she would get even more offended if i said this. What do you think about this and have you ever had a bf that cumed in his underwear befor? Did you feel embarrassed or proud?