Well damn, 2 minute kiss? Hell yea that's cheating, if my boyfriend did that with another girl, I would sure be pissed as hell and leave his ass (well...probably not as graphically but yea). Seriously, you probably wouldn't want her making out with another guy...Her new "hot" neighbor. And it's probably a good idea to tell her, if you plan on keeping your relationship...Building on lies/dark secrets is not a good thing, I'm a girl, I know...Hopefully she'll see past it and forgive ya, but you never know, that's not really something somebody wants to here...