Yes because here the seme and the uke were best friends so we can imagine that the uke was always in love with him but didn't realize it because he was so used to be always together with his friend. So when the seme confessed his love he understood that he was also in love and it was useless to resist :p
It's pretty easy to confuse love for friendship and the other way around, it's a really common topic in yaoi ╮(￣▽￣)╭
That's assuming there is a concrete boundary between the two; for a lot of people it's not such a simple dichotomy.
ok I m a super fan of yaoi but really sometime it's like ... really?!?
Like in the last story ... I don't think a guy will switch gay just like that... will they?