It takes time really. Men are going to go faster without a condom because there is more friction for him. That's just how it is. You can either keep trying or go back to condoms. One way to delay his o is when he feels like he is close to just stop moving (both of you) and usually that will help prolong the experience. Remember, birth control pills are not 100% effective anyway, especially if you do not take them at the same time everyday or if you forget to take pills.

I am a male and the same thing happened to me that is going on with your boyfriend. A condom takes away a lot of the feeling. This is why men never want to use them. He will tell you himself that it feels a million times better. It took me a while to get back to a time that I felt okay about. To be honest he will never get back to the length with a condom. You could tell him about some creams that desensitize the feeling. Just watch out b/c he might feel that your trying to tell him your not satisfied this way. The more he gets used to not using one the faster he will get use to it. Don't expect results anytime soon, this will take some time. Trust me on this he wants this more than you do.

Hello ,
bherr is right it going to take him some time till his muscles strenghten

happy holidays