Love my bf but want to date around a bit?

My bf rn is the only person I’ve ever dated (started dating at 17), only person I’ve kissed, slept with, and all that. We’ve been together 4 years now. I love him so much. He treats me so well and even after 4 years he’s just as, if not more, affectionate and caring as when we first started dating. I for sure see a future with him. I see him being my husband, I see buying a house with him, having kids with him and all that. BUT what I sometimes get worried about is if all that does happen, I’ll have never done anything or dated anyone else. And I kinda like the idea that we would’ve gotten to know each other at a young age and built a relationship from there but I can’t help but wonder ...

I’m not lesbian and I don’t even think I’m bisexual but I would love to experiment with a girl to know what it’s like. Or know what it’s like to not turn down guys when they hit on me. Or go on casual dates. Or not worry about a relationship.

I love my relationship so I’m not saying I wanna leave, it’s just this feeling I get every so often. I’ve talked to him about it and he says if we need to break up for a few years or something so I can figure out myself then he will do that and he will wait for me. But idk how much of that was what he really felt. I know he’s had thoughts when he’s out with his friends about what it would be like if he was single but he never did anything.

Anyone else ever felt like this?? Or anyone married to the only person they’ve been with? And did you feel like this and does it get easier to forget about the feeling??