I agree with Sherie that DP needs to have times when he tries to comfort your son. However, you need to know when that's not working and that it's time for you to tactfully step in (even if you need to apologise to DP later). It can be a fine line between ignoring your instinct so as not to hurt someone else's feelings, and knowing when it's ok to leave an upset baby with someone else. If you can't take it any more to just stand by and hear his crying escalate, step in. It's not worth your baby getting more upset over to save DP's feelings. He's the adult and being offended is not something your baby will understand, so baby comes first IYKWIM?
They will work each other out, don't worry