Does all sperm come back down?

Whenever me and my bf have sex all the sperm immediately comes down. My ex and I his sperm all didn’t come down at once. Bt my bf now it all comes out as soon as I stand up is this normal? Does it mean it’s dead or something? We got sperm analysis and all and his sperm is above normal number but the morphology was 3.5 and has to be 4. that’s the only thing wrong. Advice?