It may be that your partner's abortion has caused you emotional or spiritual distress. Some men feel angry about not having a legal say in the outcome of the pregnancy, or for trying but being unsuccessful. Some feel guilty for the physical or emotional pain their partners struggle with during or after the abortion. Some men feel shame for not feeling as bad as their partners about the abortion. Some men are confused when their partners are OK with having had an abortion, but they themselves are depressed, guilty, grieving, or shame-filled.
There is a whole chapter for men in Peace After Abortion. Men don't get much recognition in our culture for having feelings. You may feel isolated and weird for having strong feelings about an abortion. You are not weird at all, but it may be hard to break down the sense of isolation. You can begin to understand your feelings by reading about the kinds of feelings women might have after an abortion.
The unfortunate stigma that still surrounds abortion makes it hard to talk to other men about your experience and discover that some of them also have strong feelings about a partner's abortion. Talking about it is exactly what you need to do. If it doesn't feel safe to talk to your friends about this, give yourself the gift of a few sessions with a therapist who can listen and help you sort out your feelings. It's tough work sometimes but it can help you feel like the man you want to be. If you do want to talk to a therapist, there are some suggestions for how to select a therapist on the resources page.