Is my bf cheating?

I'm seriously freaking out. He's friends with this girl. But he does things for her he won't even do for me? He drove 6 hours to see her for like 4 hours, he LET her touch him then apparently he got "turned on", yet again he didn't say anything to her??? Now I think he's seeing her without telling me.... I just feel like he's cheating with this girl but doesn't want to let me go