That was his bedroom, Eman5805. And besides, there are two reason why he can't be comfortable kissing a girl:
1.) Kissing a girl would indicate that he finally has something analogous to a normal life, and it frightens him because every time something good like this happens to him, he loses something important to him.
2.) Zuko has so far??shown an attraction only to dark-haired, beautiful girls, and Freudian psychology suggests that most men are subconsciously drawn to women who remind them of their mothers. And these girls bring painful memories to the surface.