Would having sex with my girlfriend mean I relapsed?

Biblically and scientifically yes. Biblically sex is not a mere physical act but a spiritual one and creates soul ties and allows demons of lust on you the same way porn does when sex is done outside of marriage. Scientifically if you have sex with your gf you’re still stimulating that dopamine in a similar way to porn in your brain while it hasn’t fully reset itself and healed itself from porn yet. I’d recommend staying away from all super high dopamine stimulating activities besides working out to help your brain recover faster. The reason working out is okay is while it does release lots of dopamine, it also helps protect existing dopamine neurons from degeneration which will help your brain recover faster. Even eating lots of junk food a day in a long session can cause a dopamine high similar to porn and be similar to a reset as far as your brain is concerned. Even from a secular perspective you should probably abstain from sex for at least a good month or 2 after not using porn so your brain can fully heal itself.

No have sex with your girlfriend all you want, porn is the bad thing here not ejaculation.