Guy not ready i guess.... ?

I've been with my partner for 4 years and 6 months already, we have a 1yr and 7months baby.. We live together, We have problems as any other couple, we have a good happy life even more now that my  baby girl is with us! But now i've been thinking about.. 
He has never proposed me, maybe he is scared or just not ready to get marry, it confuses me in what if he really doesn't love me ? 
​I see all this couples either engaged or married.   
Is it just me or any other similar experiences?