Did I miss something? Are they lovers and blondie is cheating or are they just childhood f...

Very bias against the ML(blonde) and MC romance and ML in gener. However think I understand what's going on.
Childhood friends that had some tension going on. Seems like MC would be the type to stick with the ML cause he had a crush on him, but never confess cause they are both guys or the ML had girlfriends and fwb on a rotation(so he assumes theres no place for him in the ML heart as someone romantically special). The ML knows that the MC likes him since they were kids judging by how he wanted the MC to make him rings and flowers, and the ML gets jealous if the MC attention is directed at someone else and would try to manipulate the situation to bring it back to him. ML probably got some loneliness thing that causes him to seek attention and any semblance of love from others, and it seems from a young age he knew that MC could give him that love but he'll settle for looking elsewhere. I cannot forgive that in chapter 3 the ML almost had a good romantic vibe but brought up other people as if the MC biggest contribution to their relationship includes helping the ML find girlfriends.
Anyway it seems from chapter 4 both know how they hold some romantic feelings, but the MC currently is looking for someone else to love cause he most likely can't trust the ML to be monogamous even if the ML will ignore his girlfriends and say he'll drop them immediately.

They're basically childhood friends but the MC did have a crush on Blondie but he realized that Blondie is a serial dater and didn't think he could fit into that. It's obvious that Blondie has a crush on him and is really possessive over him too that's why we see him saying and doing things that the MC describe as his type. Although he is doing everything the MC Likes he still goes around sleeping with others cause he said he is lonely. So for some odd reason Blondie is afraid to take the next step with the MC he flirts with him and then throws it off as a joke.( I think it's because he can't stop sleeping around due to his loneliness and childhood trauma he is dealing with & is worried he might just cheat on the MC too). But long story short they both want each other and is pretending they don't. Both scared to put it out there.