Why not try to seduce her? Woo her on all levels — romantically, emotionally, socially — and don’t pressure her. It’s only been four months of dating, and if you like her enough to get through this transitional period where she’s breaking up with her ex-boyfriend, separating from him physically, and selling the house they shared — which is definitely enough to give anyone the type of stress that would affect their sex drives — then slow down and make the relationship more about romance, for now, and the sex will follow. 😉