Apparently he does have experience
Juyoung complained to Doyoung because he didn't want to do it with her "You've done it with other women, what's so strange about doing it with me?" said from her dense mind bc he clearly loves and cherishes her. That was surely another reason why his exes were so angry, even with intimacy they couldn't make him truly fall in love with them and they gave up.

I'm still curious how far did the ML go with his exes.
I'm still stuck with FML being a virgin and not knowing about the ML.
I can accept trying to date others to get over the FML, but I still hope he didn't go all the way with them.