I am a 28 yrs old guy, in a 5 yr relationship with my girlfriend. We both love each a lot. But since last August our sex life is on the decline. I am not able to keep erections during sex and can only get off while masturbation. This is putting a lot of strain on me. She is very understanding and brushes it off, like no big deal... but I know that she's frustrated too. We were in a long distance relationship for 2.5 yrs in which we saw each other once in 3-4 months and now she has moved back in with me. She is the only person I have had sex with and same for her. When I was away from her, I masturbated a lot to different kinds of porn. I even tried crossdressing and now I love watching tg porn. She is totally fine with that too. But I just can't get my erections to work during sex. I am on carbamezapine (tegretol) and valparin chrono medication for my seizures for over 9 yrs now. Could that be a reason for my reduced sex-drive, as I don't feel like having sex in fear of failure. Or is the fetish porn that is harming me. I am in a lot of stress over this problem, my studies and feel helpless sometimes. Need help urgently.

I think you need to ask a doctor regarding the medication. Medications in themselves can have certain effects and then those effects can be different with combination of other drugs. Any of your suspected reasons could be it in my opinion.. the mind and how it connects to experiences is a possibility... but the first question is about your medications. Consult your doctor immediately so that you can find your answers instead of it hurting you mentaly and emotionaly

It can be the medications, talk to your doctor on that. But also if you masterbated a lot, you get so used to the feel of your hand, and that tightness, you have at times trouble with real sex. Are you still masterbating or have you stopped that now with girl friend here.

What Fr_Chuck said. Especially with how your are masturbating.

Also have there been any major life changes/new stresses? Lose of job, moving, stress at work/home, family troubles, or the like. Those can have some effect.

Look into the medication, though I would find it hard to believe that it is a issue now after taking it for nine years. It is the same pills though? Not same medication but different manufacturer?

The medication has increased in power, but has been constant for the last 5 yrs. I still masturbate sometimes, but try to save it up for her usually. In my mind, I want to have a good passionate sex, but my body doesn't work. After a failed sex session, I don't even feel like masturbating even though she insists that I masturbate to get a release so that I feel better mentally. I want to get her off and please her, even though I don't ***; but she doesn't like that idea as she wants us both to enjoy sex as much. Sometimes, we even masturbate together, while kissing and cuddling, but its just not the same. So do you think, my neurologist would be the person to ask first or should I consult a sex expert or whatever?

I would start with your doctor, Also try not doing any masturbation for 2 or 3 weeks before you see her.