I think my boyfriend is cheating .. why do i still love him?

hi guys. i've been with my boyfriend for five months now & it's been quite intense, i've been living with him for the past six weeks which at times has been fab. love waking up with him! before me he was in a relationship for 9 years which ended about 3 months before we got together. about a month into our relationship, i found texts to another girl & his ex; the ones to the girl were saying he wanted to 'skip the dinner and just go straight to hers' and later ones indicated he had been with her. the ones to his ex said he missed her so much. recently he has been seeing his ex as he owes her money but didn't tell me he was going to her house & he's still texting loads of other girls but i still can't leave and i'd like some advice that will give me the to say goodbye basically!! when he's not out at the pub and doing these things then he's the nicest boyfriend ever, he takes me out, treats me properly and is soooo affectionate and he talks of having babies & going on holiday with me next year. whats wrong with me???????????