Trouble having sex on the spot.

So my husband has been wanting sex a lot and I am not always in the mood for it. Most of the time he is ready to go and I am just on the computer or doing something else and I just can't get in to it when it's cold turkey. I need to be turned on first. He is getting upset because I didn't want it but I just can't do it like he can. Anyone similar or is it just me?