Is it love still ?

My fiancé and I have been together for almost 6 years now. About almost 2 years of being together we became sexually active, after that it was 3-5 times a day ! But after we had our son it slowed down to like 5 times a week....then eventually baby #2 came. Now it's normally 2-4 times a week. Besides the sex, we have been through hell and back (a few times) together an we love each other to death for sure.. But I just feel like the past month since he started his new job mon-fri 9am-5:30pm he's slowly and slowly drifted away. We live together but as soon as he gets home he just sits on Facebook or watches YouTube videos, barely ever wants to spend time with me,(he will spend some time with the kids but not much) and passes out super early. We haven't had any sex in over a week which is really weird for us and I just feel like he's not attracted to me anymore and just doesn't love me as much. Maybe I'm overthinking but he's been pretty mean to me thinking I got life easy cause I go to school for a couple hours everyday and come home to take care of our son. He just picks fights a lot (I mean I'll confront him about things too but he starts over stupid shit cause he can't find a shirt he's looking for and starts talking shit to me for example) I mean I know he still loves me and I love him too but I don't know if this is like the beginning of the end, ya know ? Opinions please.... Am I overreacting or overthinking , or do you think I should be worried ...? Thanks if you read this BOOK to help me out......
UPDATE: since I can't comment without it being anonymous, I do let him know how happy I am for him to be home and am super nice and let him know how proud I am of him and happy to be with him, I also brought up the sex topic too. But he just comes home in a bad mood and yells and me or makes it very clear he's aggravated and just goes in the room for hours and sits on his phone. I tried to confront him (in a pretty respectful matter) not too long ago basically saying "why dont you do anything with me? You've been watching YouTube videos for like 3 hours now..I just feel like you're not happy with me anymore, like you're getting tired of me" and he said "why do you have to be such a bitch?" and "yeah, I am tired of you ! (Yelling)"