there were a lot of 'ten' examples in there as well. i think with martha we are defining what was different and special about the rose/doctor relationship. Look at the conversation in school reunion- its because he loves her he tries to push her away like sarah jane. He doesn't want to see her whither and die.From then on he tries multiple times to say 'i love you'. I think if he was in love with martha he would know to say what he feels before he loses that chance again.