Depression can be ofren lack of spiritual energy.
If your ex-boyfrend is a psychinc vampire (maybe it's the case) he could be draining energy from your actual boyfriend; if they know each other this can be possible because your ex unconsiously want to destroy your actual partner as a form of revenge/control on you (I'm guessing).
It can also be possible that you are depleting his energy because you come from an abusive story and now you (unconsiously, not willingly) attach yourseld to your actual partner's chakra in a hard way, to get some relief by your inavoidable psychological damages from your past relationships, like a sort of "relief" you want from him.
Meditation on the SUN, the 3rd chakra, the rune Sowilo, simply spending time under the direct Sunlight absorbing it using the basic meditation (see the JoS meditation pages) is very helpful for both of you.
In case your old boyfrend is the concern, try to program your aura to repel him and his energies