He did say "I want to be able to say 'let's become adults together' to someone too" so it ...

He did say "I want to be able to say 'let's become adults together' to someone too" so it means:
A- He is available
B- He is looking for romance
C- It could be a hint by the mangaka to say that the next story will be his, maybe he'll go somewhere else thinking he is going to get two guys together but ends up discovering he is matching himself with a guy... preferably a hot seme since I want cupid to be a uke :p