You are being somewhat unreasonable and he hasn't given you a reason not to trust him. I can certainly understand your position. Many women would be very nervous. Unfortunately he seems to have a personality where he choose to interact with women and there is his business prospects. I see this as your having two choices. One is to have a relationship with him and learn to trust him. He isn't going to change. This will take work but it is possible. It must include a lot of communication and reassurance. The other is to let it go. If you really are uncomfortable with his interactions then that may be your best choice. You can't have insecurity in this relationship because he has been doing this a long time. It's your decision
If this has been helpful press accept
Can I let him know that I need more reassurance from him? We already communicate very well. what other ways could we work on this?