I [26F] am concerned about my [27M] boyfriend's introvertedness

My boyfriend and I have been in a LDR for a little over 6 months. Since the beginning we have been talking every day, sometimes all day. We recently spent two weeks together, and the day after going back he told me: "we have just spent two weeks together, now I need to enjoy some alone time".

I think I'm relatively introverted myself, after parties/gatherings I need a few hours to watch tv shows, read etc before I go to sleep. The only difference is, I don't feel that way with my boyfriend around. I feel like I can "recharge" with him around and/or by doing stuff with him. I can't help but feel hurt that my presence is unwanted. Other than that, we're in different time zones. After I go to sleep he has at least 6 hours where I don't bother him in any way (texting/calling) but apparently he needs more time to himself during the day as well. I just don't understand since it was never a problem before. We both have busy lives but when we had some days where we were both free (not working, no class or no plans with friends) we'd often spend all day on the phone, watching movies or whatever. We'd be on the phone, but still manage to get stuff done (grocery shopping, laundry, draw etc.). I don't understand why he's being so distant all of a sudden. Since he went back, we haven't talked much at all.

Other than that my main concerns are:

• if he's feeling this way just after spending 2 weeks together, how is it going to be when we're living together permanently?

• We have discussed kids and we both want them sometime in the future. With my bf needing to "enjoy alone time" (this much alone time) I worry that, most of the time, I'm going to be the one taking care of the kids on my own.

Are my concerns invalid? My bf thinks I'm blowing this out of proportion.

Any extrovert/introvert couples that have made it work?

tl;dr: Boyfriend needs time to himself all of a sudden. I'm starting to worry that it'll be a problem for us in the future when we're living together and have kids etc.