I felt like this a lot when I was married (I am divorced - I split up with my husband about 2.5 years ago). I didn't have a lot of sucess solving it but that's only part of the reason we are no longer together. One thing I did do was instead of telling him I wanted us to spend more time together I told him an exact time/day/event. So said I would like us to go to the movies together this week, or I would like us to go out as a family to the park on Sunday morning. The theory was that then he didn't feel I was nagging and he knew exactly what I wanted. I know exactly what you mean though about wanting him to want to spend time with you. I read a book about love languages and different people express love in different ways. Perhaps your love language is quality time and his is something else - he may think he is expressing the way he feels but its just not in a way that means love to you. Here is the link to the website that explains it .
5 love languages
One thing I will say is that though I felt completely alone in my relationship it is still alot different to actually being a single parent. Think very very carefully before you leave, especially if there is still love in your relationship. Being a solo parent means doing every single thing in your house (housework, groceries, cooking, lawnmowing, bill paying etc) and making every decision. It can be very exhausting and lonely. No matter how alone you may feel, being actually phyisically alone means very little emotional or real support and an increased amount of stress. I don't regret leaving my husband but there were alot of other reasons that went into my decision.
Good luck, and I hope some of that helps.