My girlfriend. URGENT!!

So me and my girlfriend have been in a very loving relationship for almost five months. I am known to be very worrying and to overthink a great deal. Recently I keep on worrying she might find other people than me attractive and although she has tried her hardest to reassure me I am the only good looking person in her eyes I find it very difficult seeing all these people with Better body’s on tv. I also worry about when she watches tv when they are naked or in swim wear or something like that. I don’t know how to overcome this overthinking and worrying so I feel so bad for my girlfriend coz she has tried her hardest to make me not worry but I feel like nothing will make me stop worrying. I just need to know how to stop worrying she might find other people attractive other than me. Any tips on how to overcome the thought of her being attracted to other people?