So at first there is this boy who didn't have confidence to have sex with his girl. And then there is another boy who thought that it is because the first boy got a small penis and try to stole his girl, NTR style. But actually, the first boy's penis is huge and his previous girlfriends afraid of that.
In the end, the first boy ended up with a harem of his current girlfriend, and the second boy's girlfriend.

Is there anyone could help me with the title? or any clue at all is appreciated.
I remember it not being too dark of a story even though there is ntr in it. It's quite comedic.

thanks

Well, actually, the second stolen girl was just a sex friend with the other guy, but yeah. I remember this. I need to check the actual name a bit later when I get home, but expect an update / edit to this post within the next 8 hours or so.

Edit:

And here we go:

Artist Yoshiura Kazuya

Tank Ibitsuna AKA Love Distortion (YOSHIURA Kazuya)

Chapter 8 - Little problem (yeah, hilarious in the context.)

[img]http://i2.kym-cdn.com/photos/images/original/000/028/438/5700.necropost4kobf7.png[/img]

whoa. fast response. Thank you very much Baalzebup.
I'm actually forgot lots of the details of this manga because I'm sure it's been a long time already. But now that you point it out, what you describe sounds about right.