I've often felt like this as well especially when my husband is away for work two weeks at a time (I don't see him half the month). For me I try to keep my self busy and productive but most of all God has helped me a lot with the loneliness. It helps to find what brings you joy whether it be listening to music, dancing, drawing, going for a walk, reading, etc. don't lose out on fun. Exercising helps a lot too, though don't over do it being pregnant. Take it slow so as if you were still able to have a conversation. Trust me you are not alone! Hope this helps :j
I love this verse, 'Fear not, for I am with you; Be not dismayed, for I am your God. I will strengthen you, Yes, I will help you, I will uphold you with My righteous right hand.’ (Isaiah 41:10 NKJV)
Sometimes I just try to rationalize with myself and have self-love. When people are available I vent a little, or a lot depending on who it is lol