It sounds like he is trying to get closer to you. It may feel a little creepy. I think you should try to talk to him about how this has made you feel. This might feel weird but it will help you and him communicate a little which will allow you to be able to see how he is. Maybe even trust him a little.
It's hard seeing your mom or dad date someone who isn't eachother but with some cumin comunication it can be a little easier.
If you need someone to talk to you can always
pm/
vm or email me from my page if you want to talk.
Stay strong. All will be okay in the long run.