Communication is a key...

To start with, I'd like to say that without my husband, motherhood would have been harder an experience than it is. I feel that one thing that you are not prepared for when expecting a baby is how much harder everything gets once you are pregnant and there is the nagging feeling that once the baby is there, life will never be what it used to be again and it is the end of staying up late together, going on dates, wearing nice clothes, make up, showers of more than 2 minutes, home tidied, dishes washed, etc. Pregnancy takes a toll on a woman's body, it makes you tired, makes you feel like you can't go anywhere if you do not know where the next lavatories are, it turns you into a hormones bomb and you do not feel like yourself anymore. Your husband seems like a foreign person by moments and when you try to talk about your feelings you will either start crying or laughing and end up upset at him. And he will have no clue what this was all about.
Something very hard about pregnancy is remembering that your partner is in love with you (if he weren't he would have ran away the minute you told him about your future arrival), and since he is not in your body, is not a woman and never will be, well, he probably has a very hard time understanding what you are going through. You need to talk to him about it, and you should not feel guilty, he needs to know you still love him and what he can do to help you. Talking with my husband I found out how worried he was for me that I looked so tired, that he was scared he might lose me and that he wanted to help me all he could through this.  
I did feel guilty about how little I seemed to accomplish with my heavy body, I also had to tell him that I could not stand him eating onions or having chicken tikka or southwest sauce on his sandwiches anymore and that something about him was different. It turns out that with the pregnancy hormones, the way he smells was different to me. I am not saying there that my husband smells, but every human being as a body smell that is exceedingly discreet but unique, that is how for instance your baby will know who you are instantly when coming out of the womb. During pregnancy, your hormones change the way everything smells and tastes and it is normal that you feel like there is something different about your husband, and you'll see that the minute the baby is there your husband will feel just the same as he was before you were pregnant.

Lilly loves spending time with Simon. And he is crazy for her, so it is a relief for me
when he comes home in the evening or when he is off to know that if I need time to myself I have
someone I trust who is willing to take care of Lilly.

Anyhow, the point of this is communication is VERY important...and you need to work on it during pregnancy if you want any of it when the baby arrives, and you will need your husband or partner when the baby is there. The odds are that the resident of the other side of the bed will be much more responsive to helping you with the little angel in the middle of the night if he has had a vocal reminder of how much you loved him and were grateful for his presence during the past 9 months. I would never have expected anyone to read my mind before I was pregnant, yet I did notice that it was pretty easy for me to start resenting Simon for ridiculous things such as the bins not being emptied or a sock fallen out of the laundry hamper while if I took a second to think rationally before getting upset and saying something hurtful I would realize that he would not mind a bit taking the bin bags outside and that I could pick up the sock. Tiredness makes everything seem worse, it is not your fault if you experience it, it is the price that comes with motherhood, so take the time to think things through and to ask someone to help you, don't isolate yourself, communicate your needs :)