I know EXACTLY what you mean. My bf also has what I'd call a small pencil dick and it's been ruining our relationship from the very beginning. He even had problems deflowering me. We cant perform any positions since his dick keeps slipping out. He often goes soft even inside my pussy. When he gets hard, he usually cums instantly. Luckily for him, he was and still (for the time being) is the only "man" I've had sex with so I had nothing to compare him to. Now that Ive tried a black dildo I know what Ive been missing. So to answer your question I think it cannot be dealt with. The only way is to either try to save the relationship by cucking him (that's what Ive been working on) or break up with him.
P.S.: now that I've checked out the pic of your bf's dick, I'd say he's the same size as my bf's pencil dick (though my bf is uncut). Pencil dicks are really the worst :/ Hit me up if you wanna talk about it