Just imagine having only two people in your entire life that you're close to and care about. On one hand, those two friends are awesome, but on the other, when you're not around them, you gotta feel kind of lonely.
When he mentions Genesis having beaten all of Loveless's quotes into his head, he's smiling about it, so you can tell that even if he was tired of it at times, he still finds it funny.
I also think if Genesis and Angeal were still his friends when he found some stuff out, he wouldn't have reacted quite like that, especially with those two to help him figure things out and hopefully keep him calm.
It doesn't help that Genesis is the one that tells him all that crap in the first place.
Wait, wasn't this thread supposed to be about Sephiroth's potential girlfriend?