I feel like my boyfriend is cheating?

So my boyfriend [18M] and me [17F] have been dating for a while now and it's now a long distance relationship and I always get this feeling that he is cheating on me. I have been through his phone I have his social media account passwords. But still can't shake of this feeling. He always tell me he loves me too much and is always available for me. I don't know why I feel like he is texting another girl. Is it normal to feel like this in a relationship?