Questioning my sexuality

Okay so I’m 19 and I’ve been in a relationship with my boyfriend since I was 15. But I’ve always been curious about being with girls, especially because 80% of the time that I watch porn I tend to gravitate towards lesbian porn. Anyways today I talked to my boyfriend about it( and he has known about what I watch and how I’ve always been a little curious but we never truly talk about it ) anyways he said that since it’s been on my mind lately that he would be okay if I had sexual relations with another girl. This shocked me because he would always make joke about how he would watch or have a three way, obviously joking in the past. But this time he said “ no I’m serious, it’s not about me it’s about you and your sexuality if your bisexual or bi curious I would prefer you to go out there and try it out. If I were in your position I would want to know and would want to experiment.” I still don’t know what I want to do, I love him and I do still see it as cheating and just using another girl for my curiosity which isn’t fair for her. He said he wouldn’t view it as cheating and that he trusts me, but idk, i guess I’m just asking for a different opinion and some advice.