Ok, just to clear up some concepts. The flatline, from my experience, is a way of your brain telling you that it is not getting enough stimulus. Your flatline may not even have anything to do with your actual sex drive. Do not worry about performing with a partner. You may find that a real partner will arouse you even though you're in a flatline (which has happened to me).
If you are not aroused though, this just means you need more time abstaining from PMO and MO. Also means you must continue rewiring with real partners in a healthy way (do not watch porn with your partner, do not overdo the orgasms, do not feel pressure to perform). Let your partner know about your condition so you can continue to apply proper treatment.
Do not avoid dating because you have PIED (which is what I used to do). This will only further inhibit your progress by isolating you, delay rewiring and add temptation to MO or PMO. Take as much time as you need to feel ready but don't overdo your alone time.
The thing is, your brain is craving porn and so it's making you numb so you feel you need an extra kick. Do not do this. Continue to abstain from PMO (Preferably MO as well). I myself will not be MO'ing for a LONG time.
As for your question scorpion, masturbating to porn will 100% throw you into a flatline. Nofap does not throw you into a flatline, a lack of satisfying your brain's dopamine kick requisites causes a flatline. Your brain needs time to go back to wanting normal, natural surges of dopamine.
I relapsed around two weeks ago Gavalar. I have little to no morning wood at the moment. Very few horny moments in my day. However, morning wood doesn't really mean anything sometimes. I've heard of guys that have morning wood and still have problems. However, this past weekend I was able to have an erection even though I drank a lot beforehand and was in a flatline. It did take a lot of time to get an erection, but I think it boils down to being patient, honest with your partner and taking pressure off yourself to perform. Being with a real partner is different somehow.
I highly recommend you guys read this article:
https://www.yourbrainonporn.com/porn-induced-sexual-dysfunctions/help-i-quit-porn-but-my-potency-genital-size-and-or-libido-are-decreasing-flatline/
Knowledge is power.
Take care of yourselves guys.