hey...nothing wrong with being alone and being the eldest one...trust me if you feel alone like this, if even you are with somebody still you feel lonely...you got to work on yourself....
I am like you too...but I'm trying to change and I can see the change little by little...
I have three sisters and I'm the middle one, the only lonely one...my sisters get so excited when they see me dating, then another disappointment very quickly, within couple of months...hehehehe....
Try to connect to people who are single then you feel less lonely, I avoid those who are giving me tension and stress or constantly asking about my dating and love life...I hate those questions....and sometimes, I tell them something nasty to stop them!
Beach is the greatest place ever....I went to beach on Saturday and my friend was with me, but she left soon....and ironically, when I was alone, I felt even better, because I start paying attention to my surrounding....I always wanted to try surfing...that motivated me to start talking to one of the surfers and he was so nice and gave me his friend's number who is a instructor...basically, the key is getting connected with people and not letting loneliness get into you....
stop thinking about it and you will be fine...most people are alone even if they have partners....
I feel lonelier if I have a partner who doesn't care about me!

take care
Marjan