Time is the best one... loads of people don't actually make enough time for their partner. But you've already tried that by the sounds of it. But still, don't rush or focus on it.
My girlfriend struggles sometimes too. It mightn't work for everyone but she finds one of the best things is basically for her to keep busy! If shes pleasuring me and touching herself she doesn't worry about coming or over focus etc.. and by the time she gets to the stage where shes ready shes so horny it doesnt enter her mind.
If you and your partner are willing to use toys during penetration then that might be a good way to help you relax.
I do understand where you're coming from, she used to struggle more as she felt if she did'nt come it would upset me, so not only did she have her pressure she imagined she had mine too! If you can convince your OH that you not coming isn't the end of the world it might allow you to relax more. The fear of upsetting your partner may make it too hard on you. Show him that you don't need to always come to be satisfied.
I'm sure if you have a wander round the forums you'll find plenty of advice put way more eloquently than my spare of the moment comments!