Boyfriend traveling abroad with ex girlfriend - does he still have feelings for her?

I've been dating this guy for 6 months. 2 months into the relationship, after he met my parents and just before I was about to meet his parents, he told me that he felt guilty because he had booked 2 trips abroad with his ex (one in August and one in October). He insisted on taking the trips, told me that he's just friends with his ex. They dated for 5 years and broke up 3 years ago. The odd part is he told me that he didn't want to tell her about me (he told me they don't discuss with each other who they date), told me that he would be sharing a hotel room with her (to save money) and he hasn't had a relationship with anyone other than me since they broke up. He also won't add me to facebook - I know he uses it (he's been on it around me). My thoughts are that he has many pictures with his ex traveling abroad (they've been to several countries together) and he doesn't want me to see them. This whole situation is odd - he told me that they didn't work as a couple and continued to date mainly so they could continue to share their passion of traveling. He did however tell me that they fought on their last trip back in August. Why continue something with someone if you can't get along with that person and why hide/jeopardize promising new relationships?
Boyfriend traveling abroad with ex girlfriend - does he still have feelings for her?
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