I've been planning a trip to my college town for a reunion with my friends for nearly 3 months now, and I invited my boyfriend to go with me. He agreed and I made all of our hotel arrangements and such for this coming weekend, and last night, he tells me that he's not sure he wants to go because he "doesn't want to ruin everyone's time." I'm not sure what this means, and I find it very rude to cancel last minute. He's given no other explanation, and it makes me feel like I'm to blame somehow. Also, after months of dating, we finally had sex this past weekend, and it feels like he's backing out on this trip because he finally got what he wanted from me. Could it be that sex ruined this relationship?