Masturbation is totally normal and everyone does it. It's nothing to feel guilty about.
Porn is also normal...however don't confuse it with the real thing. I did actually know a guy who was single for a long time and when he finally met someone he really liked it caused him some problems.
If your in a relationship I agree you should be considerate of your partners feelings. If she's insecure or you are having issues it can cause problems.
Most women I think are ok with it as long as you're still handling things on the home front ok. I wouldn't suggest lying about because that could cause some trust issues.
Just try to have some open communication...if it becomes an issue.
Just my opinion.
It's gonna be OK.