I'm here to find a real reason why i can't be with my girl without a problem, without her mom not wanting me to be with her cause of me religion or her being scared to be kicked out her religion.
Her mom won't want you to drag her out of the religion and subject her to being destroyed at Armageddon any day now.
She will not necessarily be kicked out of the religion, but she will be made to feel bad about going against "Jehovah's" doctrine of marrying "only in the lord." If she confesses to premarital sex, she is subject to discipline up to being kicked out. If she celebrates a birthday or holiday, the same. If she manages to not tell them about these things, she will feel guilty. Basically, she will feel bad unless she comes to terms on her own with the thought that Jehovah's Witnesses are a dangerous mind control cult.
Even after all that, you might have kids. She won't want them being anything but JW's. She won't want them celebrating anyone's birthday or any holidays. She will want them to actually fear sharing birthday cupcakes at school when someone's mom brings them in. She will want them at all the meetings, not to have life-saving blood in a medical emergency, not to participate in school sports, not to go to college.