Oh that’s a tough one. The first piece of advice I can give is to remember what you’re feeling is just lust and that you genuinely care for your bf. it’s tempting tho. I have lusted while in relationships as well. You should just really talk to your bf and let him know that you want to take it to the next step. And also don’t let him limit your sexual experiences you are allowed to explore and find yourself and what you like on the understanding of what won’t hurt his feelings. Communication is honestly the key to anything. Don’t keep it to yourself it will drive you two apart. :/ I hope this helps! Have a good day. Inbox is always open