I have really bad trust issues

So I’m currently dating a guy and I love him a lot and we are a really cute couple and all his friends love us but I notice he’s still close with his ex. Idk if I’m over reacting or not but I do struggle with trusting people and when it comes to being loyal. I’ve also noticed he gets really horny often and I’m not sure if he’s just like that because he’s attracted to me a lot or if he’s one of those types of guys who just wants sex. I know I’m probably over reacting and just thinking of all the negatives but I don’t know how to stop being like this. If anyone can relate to this or has any advice let me know please