Yeah it's weird, even before the kiss Aleks seemed to kinda bully Dominik yet, he was nice to him (shower scene and prom scene before kiss) and is obvious that Dominik liked Aleks (Judo scene where Aleks is fighting some other guy, Dominik stares dreamly at Aleks). Then the kiss happened and they became popular and everyone thought it was a joke, maybe that's why we see Aleks being openly affectioned to Dominik, then the judo incident happened (which is a weird scene too, because there's no way Aleks wasn't feeling Domink hard on pressed against him) and everything went confusing Aleks was the one that published that on facebook and Dominik reacted really bad at it. My options are a- maybe Aleks just wanted to continue the "joke" so he could be closer to Domink. b- Aleks got scared that Domink actually liked him back (or vice versa) which would explain why he became aggressive towards him and posted the video (Where two hands appear and one is f**king the other one) to pass Dominik as the gay one. I really think they just were too scared to admit their feelings.