salam dear sis
there is ntg we can do, u said u were tired, den god will 4give u. Becos ur intention was nt that to purposely sit beside him, in fact u didnt even know a male will be sitting beside u. Since ur intention is clean, then no worries. This things are hard to be avoided as there are alot of non muslims in dat coutry, n they cant understand our problem. U didnt tok wid him, so thats good! No worries. Smtimes wen im tired i just sit, but i make sure da other party dun brush on me! Even today on ma way to teach, i sat beside a man, it was so crowded n i was tired of running here n dere. God will 4give u as long as ur intention pure. God judges us by our intentions more den our actions. take care