Jiraya himself admits he considers it onsided love from his perspective in the anime and manga. Tsunade herself doesn't have romantic feelings for him but still very much considers him a dear and VERY close friend. This is especially showcased when she cries in private after his death and when she bets he will die so he would hopefully return from his fight with "Pain" alive. She is was also willing to go personally as backup despite the dangers and her duties despite Jiraya objections. Jiraya also mentions in the anime (in a notably similar fashion to Naruto himself) that he loves Tsunade enough to be content to just be her side.