Will you be disfellowshipped if you date an unbeliever?
Strictly for dating an unbeliever? No.
But if you persist, you will be ostracized by virtually everyone in the congregation. No one will ever invite you to their home (obviously, referring to a non-COVID world). No one will invite you out to eat with them, or invite you to any social event. Evan at the Kingdom Hall, very few if any will come up to talk to you.
Nearly all contact with you will be limited to "encouraging" you (i.e., forcefully trying to persuade you how hopelessly misguided you are, and if you were "wise" and "want to please Jehovah" you'd drop your boyfriend like a bag of hot lava). There will be virtually no other topic of conversation between any other JW and you, aside from superficial niceties.
In short, your life as a JW will become intolerable. You will be forever an "outsider". You need to decide which you want more - to be a JW or to have a boyfriend / husband.
The fact that you are posting on this site indicates your heart may not be fully inclined toward a JW lifestyle. If that is the case, now (before baptism) is the time to cut and run.