You need to talk with him. Tell him how you feel. LISTEN to how he feels. The first step is to understand each other. Be clear if you have deal-breakers, and be clear whether he has deal-breakers.
If I am feeling very, very sad, and if spending time with my boyfriend would help me, then I would say so. Don't have him guess that it's important to you. YOU might think it's self-evident, but he might not say that was the case. You need to understand where each other is coming from, and then find a space to negotiate.
I like spending time away from my husband. And to afford that, I give him time away from me, too. Now, I haven't been through a miscarriage or anything similarly devastating (my hugs to you, OP

) so I don't know how I'd feel about needing to spend time together or apart. I like to spend time apart because my husband is NOT my *everything* -- I have interests that are not his; I have social needs that he can't or doesn't want to meet (no biggie, I love my girlfriends

); and I like to spend time away from my kids too to refresh my adult brain.
This is to say, there is not a universal belief or feeling that being with one's SO all / most / some proportion of the time is key. Nor that that person must be the ONE to whom you turn for solace at 10 or 11 pm. If you feel that way about your SO -- and it's kind of a compliment to say so -- then he should know that.
But do let him have his time away, too, if he needs that time.
If he's not able or willing to meet you part way, though, then be aware that this may be your deal-breaker issue?