Is it normal to feel jealous?
I just started to date this guy and we are a couple. Just today he asked me whether I want to watch a movie with him tomorrow and I said I can't since I need to study for a major test. I didn't know he had already bought the tickets. Just a few minutes after I texted him saying I couldn't he sent me a text asking me whether I want to watch a movie but the text wasn't meant for me it was for his friend Linda.
This girl Linda is one of his good friends who knew him before me. He told me before that she used to like him but because he wasn't interested in her, they are just friends, nothing more.
When I told him about the text, he assured me that he loves only me and told me not to be jealous. He said he asked her because he haven't seen her for long time and he didn't want to waste the tickets.
However I can't help feeling jealous about it though I told him I'm fine and I trust him. What can I do to curb this jealousy or at least show him that I'm jealous without coming off as possessive?