Dude...you got issues.

Straight up...if you feel this way about her, she needs to be willing to let the dude go, and focus on ya'lls relationship. Communicate better. Go see a marriage counsellor or whatever they are. Obviously something's missing from the relationship so you can do one of two things. Walk away, or fix it. But in order for her to focus on you, she needs to drop him. If she's not willing to do it, then she's probably not going to be worth it in the end, bro. I hate to say it...just stating my opinion. Just stating and outsider's view.