I feel weird

I’ve been in a relationship for the past 2 years. I love him with all my heart he is so pure he has never made me jealous, angry, sad, unsafe. The past three days I’ve started to feel a little bit weird. Like I feel nothing. I don’t want to lose him and every time I think about the memories or him I cry. I don’t want to lose him I love him. We’ve talked about it and he is really sad about it too. I’m on my evaluation days and I’m for sure not pregnant. Can these days be weird for a woman and make her feel emotionally unstable or it’s something more serious. Plz I need advices:(