What can I do to keep a guy?

My questions right here cause I couldn't fit it in the question box so I've never had a homecoming date don't get me wrong I've had guys who say they'll take me but they end up skipping out and saying I'm not taking you like homecoming I was going to at a different school is today and I got a text saying sorry I'm not going which was obvious a lie cause I saw that he's dating his girlfriend again and I'm a junior in high school what can I do to keep a guy I probably sound stupid for asking but I feel so worthless when guys do that and how my longest relationship has been 2 months?