I'm unclear on how condoms are supposed to be effective in preventing female-to-male contamination during "plain" sex, I mean insertion of the penis into the vagina. Let me explain.

Latex is an effective barrier to virii and germs. I get that. As far as protecting the woman is concerned, I've no trouble believing it works. The STD virii or germs are present in the semen and/or pre-cum; these are "emprisoned" by the condom, don't get out, and don't get into contact with any part of the anatomy of the woman. She's protected. The sweat of the man does not contain these virii or germs and thus no risk with the rest of the skin-to-skin contact. But in the other direction, I don't quite get it.

Heather: I have a question about STD testing, but it's together with a lot of other stuff, so I'm giving you some of the whole story.

My long-term boyfriend just broke up with me, seemingly out of the blue. We were together for several of the most tumultuous years of our lives—we dealt with so much stuff, I can't even describe it. We lived together, we lived apart, we did long-distance, we came back, we kept going. We stayed together through moves, parents condemning our relationship, changing universities, changing friends, changing careers. I feel really stupid being broken up about it; my personal philosophy has always been: no mourning over guys. Only stupid women do that. (Obviously there's some of my own internalized misogyny in there, but I'm also being practical. A woman mourning a man comes off as pathetic; a man mourning a women is soulful and sad. That's just the way it is.) But I did (bleech, sounds so gross) really trust him. I let him in my, like, inner circle of trust.

He just broke up with me because apparently he HAS to sleep with this other girl, and he couldn't even wait until he was going to see me in a few weeks. He started hanging out with this group of party guys and I kept saying it was changing him. He kept denying it—until it did. He just got his first job and then started freaking out: he started to get into drugs, to do all this stuff.

I'm seventeen. My boyfriend and I have been sexually active for five months. We always used condoms, and sex was great. We used lube and had tons of foreplay. No complaints. About a month ago, I went on the pill, and suddenly that all changed. The sex itself was better then ever. But after he comes in me, it burns the inside of my vagina like crazy. It only happens when he comes in me. Other things, like fingering or oral, don't hurt me at all. It's JUST when he comes in me.

The pain starts the second he comes, and lasts 15 to 20 minutes. I normally run to the bathroom right after sex, and get as much of the come out as I can, but that doesn't seem to change anything. We still have tons of foreplay, but that doesn't help either. It's making me dread sex because of the pain afterward, and he hates seeing me in so much pain. Is this a sperm allergy? Would douching after sex help? Is there anything I can do about it?

My boyfriend and I just had manual sex,and after arousing him..his ejaculate shot into my eye by mistake. Can this cause an infection? My eye is very red and is paining badly. What do you suggest I do??

I take oral contraception, no biggie there. I was recently put on amoxicillin by my doctor for a sinus infection. I think I developed a yeast infection as a result. I had one before way back when, so I knew what the symptoms were. At any rate, I bought one of those over the counter 3-day cure kits. However, I forgot that the goo was supposed to be inserted at night and I instead put it in during the day (triggered mostly by the fact that I started using the kit as soon as I got it home and repeated the dose at the same time each day). It's three days later and it still itches a bit down there. Did I totally botch the goo? Should I try again?

Additionally, my fiance comes home from six months of overseas military duty on Friday. I'd like to be able to sleep with him then (hence why I'm trying to get this all cleared up), but we use condoms as one method of birth control and I've heard that these over the counter yeast infection cures decrease their effectiveness and cause them to break. What can I do?

I'm 20 and have been with my partner for about two and a half years. We have a great relationship and are happy together. However, two years ago, when we first started sleeping together, I contracted genital herpes, even though we used condoms. I was a virgin before I slept with him so I knew it had come from him. I was angry and upset but he kept telling me he had tested clean at his last STI check and couldn't understand that he must have it. When we went to the GUM clinic (together) they confirmed that I had herpes but told me that they don't test for herpes unless there are symptoms present. Therefore when my boyfriend had his previous check-up (symptom free) he tested clean for everything they test for and then went on to sleep with me. My boyfriend was upset that I was blaming him and was tested again for everything they test for to prove to me he wasn't lying when he told me he was clean. He was negative for everything they tested him for....except like last time, they didn't test for Herpes and told him they didn't test for it unless there were symptoms, which there wasn't. He says he doesn't remember ever having symptoms hence why he's never had a physical check for it. I KNOW I didn't do anything wrong, and neither did my boyfriend, but I feel so bad about myself. I feel like I should have done something before we slept together, but I don't know what. I asked him to make sure he was clean: he did. We had no idea that they didn't do standard tests for herpes.

How do I stop feeling dirty and like I was irresponsible?

How long after a girl's first time should they bleed for and how heavy should they bleed?

I am 20 and sexually active. I don't have a long term partner but have had and do have various partners. I have an IUD so I'm protected against pregnancy, however I know condoms are still hugely important. My problem is that I am completely stuck for what to say to make a man put one on. At the moment, it's just getting carried away then really kicking myself later. I have to be more diligent with this, but please- do you have any advice for laying down the law? A non awkward, but still sexy way of asserting myself?

My girlfriend and I (I'm a chick) are both virgins. Is there any point in us using a dental dam when/if we have oral sex?

My boyfriend and I have sex often, and when we do we use a condom as often as possible. But when we go to get condoms there are so many to choose from! There are ribbed ones, spermicidal, ones that are specified for "her" pleasure and vice versa, ultra thin..and more. What is the difference in all of these? Do any of them really give more pleasure or feel any better than a plain lubricated condom?

My boyfriend and I had anal sex and then after went on to normal intercourse, can this cause infections?