
I don't agree with that. I would find it more akward, if he would have declared that he is in "love".
Because they only know each other by sight and till recently Jinno was having a long-term relationship. OK-I admit that Jinno was wasted and had made a move at Eichi, which wasn' t subtle at all. But in the end ist seems fairly consensual to me.
Jinno even tempts to come to know Eichi better by trying to spend time together.
So for me it seems pretty normal that his current emotions are ambiguous.
As a starter it would be exaggerated to label (sexually) affection as love.

Not to be a prude (raging hormones can be scary and such), but I guess I'm too dry a person to withstand "hold on, let me slobber and nibble all over your body whilst I figure out why I'm doing this and what I think about you (apart from yummy)"
http://www.mangago.zone/home/photo/2483030/
(ofc, seeing this from the viewpoint of a confused fictional character who irritatedly enjoys this kind of salivating attention, it's fantastic)
Communication is key! Why does no one ever listen to me?! lol... Okay, I know it's because I'm a potato but I have wisdom too!
And plus... people! Make sure you know why you are doing things! Don't just attack someone sexually and say, "I don't know why I did it. I don't know what I feel about it and how I feel about you." okay... that's a stupid move in general. If you're going to be a d-bag, admit that you're going to be a d-bag. Don't hide behind ambiguous emotions! And if you really don't know, DON'T DO ANYTHING. Wait and observe the situation to understand, then after that you should make a move.
UGH, being a potato is hard.