Being alone is different than feeling lonely. It's perfectly acceptable to feel lonely and abandoned by our loved ones. IMHO, very few, if not NONE of us can be completely alone unless we actively engage in isolating ourselves from others. After a re-read, I realized my mind is distorted about the concept of a loved one. I love some people that may love me back, but don't treat me very well - boy is that painful. I'm trying to get better at noticing the friends that are so priceless and amazing that they're family to me.
For me personally, working on myself has done wonders. LITERALLY, wonders. I look at strangers in the eye at the grocery store. I don't hesitate to say hello, how are you doing? I don't blink if I have a short convo. with a stranger. Sometimes I sit and notice - LOOK at the sheer NUMBER and VARIETY of people in this world - just in the grocery store for crying out loud. Those individuals outnumber the people that have hurt me by MILES AND MILES AND MILES. Countless people out there.
I think if we work on ourselves and open up and let the world/universe have a chance at showing us that not everyone will stomp all over our trust and feelings, we may find the world/universe (higher power/god/whatever) has a lot of love to give.
Have an open mind. Counting friends and quantifying their value almost defeats the purpose of a friend in my opinion.
My suggestion in those moments is to think of you and what you want to do. Read a book, write on this forum, call a friend (Al-Anon member if you're a part of that), etc. I'm beginning to wonder if we're never really alone. That someone, somewhere is close by, even in spirit, in voice, in writing, etc.
I'm sorry you're feeling sad and frustrated (sounds like feelings of shame too?). You're not alone in those feelings. I hesitate with it too - one of my brother's once told me that I didn't have any friends - even though I know it's logically not true - I still feel a really uncomfortable pain about it. Hugs!