I can't stay hard

The first thing to say here is that you have a very common problem. Many people will identify with your experience and the up side is that you're reaching out for some advice. I can't adequately explain just how many men find their erection isn't playing ball but end up dealing with the disappointment in silence whereupon of course, things tend to get worse rather than better. 

As a sex therapist, I would really need to have much more information than you provide to make a clear diagnosis so really my comments are from a general perspective but will hopefully give you some thoughts about what to do next.

From what you say, I would suggest that you have a couple of things going on here. The first is the fear of having this lovely new and exciting relationship trickle away because your erection has become unreliable. In this case, I can well imagine how precious your relationship feels given the lack of both emotional and physical intimacy in the last one. No wonder you want everything to work OK.

The second is the guilt you experience from the porn use. It's likely that both these issues crowd in on you once any sexual activity starts and you fear the worst which then actually happens. Often these problems are very chicken and egg and become a self-fulfilling prophecy.  

Excessive porn use can lead to problems because the level of arousal can lessen over time often leading to more usage (to try and get aroused) which then over time reduces the arousal because what's being views is no longer sufficient. How that sometimes gets played out in real relationships is that sex is just not exciting enough despite the often very hard work to make it so. Sometimes too, health issues cause erectile problems and I always suggest that any sustained difficulties get checked out by the GP. 

But based on what you say, I think with a little bit of help, you can most likely look forward to a fulfilling relationship with your new partner. There are many self-help resources out there that can help. Look out for information and support on mindfulness techniques to help you stay in the moment.  

As I've said, I don't have much information to go on but it can be a really good idea to get professional help if you feel that the suggestions I've made aren’t helping. Getting professional help can fell very daunting and like a complete waste of money because all you want is for everything to work OK without sharing what can feel so personal and private with a complete stranger. But professional help for this sort of problem generally has a high success rate. A qualified sex therapist should be able to pinpoint the specifics and work through ways to manage things differently and so achieve what you most want to happen. That route may not be remotely necessary but do bear it in mind. Don't struggle on in silence - there is absolutely no point in doing that... 

Finally though, there’s clearly a lot of good stuff happening in this relationship and whilst I fully appreciate how important a working erection might be, don't lose sight of the fact that sexual intimacy isn't just about penis' and vaginas. Try and lose the notion of 'performing' and do bear in mind that the vast majority of men experience a less than enthusiastic penis from time to time.  It doesn't mean there's anything wrong, just how things are sometimes. Sometimes letting ourselves off the perfection hook can be all that’s needed to get things back on track.