It shouldn't be up to you to be telling the g/f how much time he is spending doing this or that - that's his issue. From what we have discusses in the past, I would say, just stay out of it, unless you there is a need (or request) to "run interference" for your husband. I've had to do this on occasion, the husband takes on more than is physically possible because he feels obligated or such (he really wants to help or be there and can't say no), so I give him an out.
I have literally had to schedule "me time" on his calendar every now and then. His idea of quality time together is to swing by and take care of some of his Boy Scout stuff, before and after dinner, so I have to be extremely specific. However, this is usually for projects around the house that need to be attended to. If I don't schedule it and leave it up to him, he will schedule 3 things on top of it, underestimating how much time each thing will take and what's important to me is always last and therefore doesn't get done at all or a less than half-assed attempt.
Part of it may just be training him to form new habits where you are concerned. Schedule daily time that is spent just with you (after the kid is in bed) or such. Maybe 1 hour with the kid and 1 with just you (sex would be extra time, but cuddles might count). No phones are answered, no texts, e-mails, etc. and the g/f will be required to respect this time as well.
I seriously sympathize with you, I feel like I'm being whiny and demanding when I want attention, but if I don't I get ignored. So I'm working on ways to request the attention without being whiny (aka: before I have an emotional tear filled break down because I'm feeling tossed aside). If he focuses his attention on the squeaky wheel, then for God's sake speak up. YOU ARE WORTH IT!!!